Answer:
a)x - 4y -14 =0
5x - y - 13 =0
Step-by-step explanation:
Using substitution method to solve equation above gives:
x - 4y - 14 =0 ....eq1
5x - y -13 =0 ....eqn2
From eqn1, making x the subject formula:
x - 4y - 14 =0
x - 4y =14
x = 14+4y ...eqn3
From eqn2, substitute value of x and solve for y:
5(14+4y)-y-13 =0
70+20y-y-13 =0
70+19y-13 =0
70 - 13 = -19y
57 = -19y
divide both sides by -19
-57/19 = -19y/-19, then
y = -3
From eqn1:
x = 14 + 4y
substitute the value of y in the expression above
x = 14 + 4(-3)
x = 14 + (-12)
x = 14 - 12
x = 2
in the number 23.45 the digit 5 is in ?
Answer: hundredths place
Step-by-step explanation:
You deposit $4000 in an account earning 4% interest compounded monthly. How much will you have in the account in 5
years?
Answer:
$4,866.61
Step-by-step explanation:
Using the formular, A = P(1 + R/100)^n
Where, A = Amount; P = Principal; n = Time(year) and R = Rate
Hence, A = $4000(1 + 4/100)^5 = $4,866.61
Amount = Principal + Compound Interest
∴ Compund Interest = Amount - Principal = $(4,866.61 - 4,000) = $866.61
The mean breaking strength of yarn used in manufacturing drapery material is required to be at least 100 psi. Past experience has indicated that the standard deviation of breaking strength is 2.6 psi. A random sample of 9 specimens is tested, and the average breaking strength is found to be 100.6 psi. Test the hypothesis that the mean breaking strength is larger than 100 psi by setting up the null and alternative hypotheses. Use alpha = .05.
a) What is the numerical value of your test statistic, z0?
b) What is the p-value resulting from the test of Part A? Answer to three decimal places.
c) What is the probability of Type II error for the hypothesis test of Part A if the true population mean is 101.3 psi? Answer to three decimal places
Answer:
Step-by-step explanation:
Given that:
Mean μ= 100
standard deviation σ = 2.6
sample size n = 9
sample mean X = 100.6
The null hypothesis and the alternative hypothesis can be computed as follows:
[tex]H_o : \mu \leq 100[/tex]
[tex]H_1 :\mu > 100[/tex]
The numerical value for the test statistics is :
[tex]z = \dfrac{x - \mu}{\dfrac{\sigma}{\sqrt{n}}}[/tex]
[tex]z = \dfrac{100.6- 100}{\dfrac{2.6}{\sqrt{9}}}[/tex]
[tex]z = \dfrac{0.6}{0.8667}[/tex]
z = 0.6923
At ∝ = 0.05
[tex]t_{\alpha/2 } = 0.025[/tex]
The critical value for the z score = 0.2443
From the z table, area under the curve, the corresponding value which is less than the significant level of 0.05 is 1.64
P- value = 0.244
c> If the true population mean is 101.3 ;
Then:
[tex]z = \dfrac{x - \mu}{\dfrac{\sigma}{\sqrt{n}}}[/tex]
[tex]z = \dfrac{101.3- 100.6}{\dfrac{2.6}{\sqrt{9}}}[/tex]
[tex]z = \dfrac{0.7}{0.8667}[/tex]
z = 0.808
From the normal z tables
P value = 0.2096
A machine fills containers with 35 ounces of raisins
The correct graph will be the first one (A)
Write the expression as the sine, cosine, or tangent of an angle. (6 points) cos 94° cos 37° + sin 94° sin 37°
Answer:
[tex]cos57 = 0.5446[/tex]
[tex]sin57 = 0.8387[/tex]
[tex]tan57 = 1.5399[/tex]
Step-by-step explanation:
Given
[tex]cos 94\° cos 37\° + sin 94\° sin 37\°[/tex]
Required
Determine the
- sin
- cosine
- tangent
of an angle
The given expression can be represented as follows;
[tex]cosAcosB + sinAsinB[/tex]
Where A = 94 and B = 37
In trigonometry:
[tex]cosAcosB + sinAsinB = cos(A - B)[/tex]
Substitute 94 for A and 37 for B
[tex]cos(A - B) = cos(94 - 37)[/tex]
[tex]cos(A - B) = cos(57)[/tex]
Hence, the angle is 57;
Since 57 is not a special angle; I'll solve using a calculator
[tex]cos57 = 0.5446[/tex]
[tex]sin57 = 0.8387[/tex]
[tex]tan57 = 1.5399[/tex]
A gallup survey indicated that 72% of 18- to 29-year-olds, if given choice, would prefer to start their own business rather than work for someone else. A random sample of 600 18-29 year-olds is obtained today. What is the probability that no more than 70% would prefer to start their own business?
Answer:
The probability that no more than 70% would prefer to start their own business is 0.1423.
Step-by-step explanation:
We are given that a Gallup survey indicated that 72% of 18- to 29-year-olds, if given choice, would prefer to start their own business rather than work for someone else.
Let [tex]\hat p[/tex] = sample proportion of people who prefer to start their own business
The z-score probability distribution for the sample proportion is given by;
Z = [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] ~ N(0,1)
where, p = population proportion who would prefer to start their own business = 72%
n = sample of 18-29 year-olds = 600
Now, the probability that no more than 70% would prefer to start their own business is given by = P( [tex]\hat p[/tex] [tex]\leq[/tex] 70%)
P( [tex]\hat p[/tex] [tex]\leq[/tex] 70%) = P( [tex]\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }[/tex] [tex]\leq[/tex] [tex]\frac{0.70-0.72}{\sqrt{\frac{0.70(1-0.70)}{600} } }[/tex] ) = P(Z [tex]\leq[/tex] -1.07) = 1 - P(Z < 1.07)
= 1 - 0.8577 = 0.1423
The above probability is calculated by looking at the value of x = 1.07 in the z table which has an area of 0.8577.
W varies inversely as the square root of x when x=4 w=4 find when x=25
Answer:
8/5
Step-by-step explanation:
w = k / √x
4 = k / √4
k = 8
w = 8 / √x
w = 8 / √25
w = 8/5
About 5% of the population has a particular genetic mutation. 500 people are randomly selected. Find the standard deviation for the number of people with the genetic mutation in such groups of 500.
Answer:
4.87
Step-by-step explanation:
According to the given situation, for calculation of standard deviation for the number of people first we need to calculate the variance which is shown below:-
Variance is
[tex]np(1 - p)\\\\ = 500\times (0.05)\times (1 - 0.05)[/tex]
After solving the above equation we will get
= 23.75
Now the standard deviation is
[tex]= \sqrt{\sigma} \\\\ = \sqrt{23.75}[/tex]
= 4.873397172
or
= 4.87
Therefore for computing the standard variation we simply applied the above formula.
A cryptarithm is a math puzzle in which the digits in a simple equation are replaced with letters. Each digit is represented by only one letter, and each letter represents a different digit. So, for example, we might represent 51+50 = 101 as AB + AC = BCB. In the cryptarithm SEND + MORE = MONEY, what digit does the letter Y represent?
Answer:
[tex]\large \boxed{\sf \begin{aligned}9567&\\+1085&\\----&-\\10652&\\\end{aligned}}[/tex]
Step-by-step explanation:
Hello, let's do it step by step and see what we can find.
[tex]\begin{aligned}\text{ SEND}&\\+\text{ MORE}&\\-----&-\\\text{ MONEY}&\\\end{aligned}[/tex]
We assume that M is different from 0, otherwise we could find several different solutions I would think.
It means that S + M is greater than 10, otherwise the number of digit of the result would have been 4 and not 5.
The only possible number for M is then 1. M = 1
[tex]\begin{aligned}\text{ SEND}&\\+\text{ \boxed{1}ORE}&\\-----&-\\\text{ \boxed{1}ONEY}&\\\end{aligned}[/tex]
But then, S can only by 9, otherwise S + 1 < 10. S = 9
S + 1 = 10 + O if there is no carry over, so S = 9 + O
1 + S + 1 = 10 + O if there is a carry, so S = 8 + O
So O = 0 or O = 1. Wait !? M is already equal to 1 so O must be 0
E cannot be equal to N so 1 + E = N, meaning that there must be a carry over from column second from the right.
and E < 9 as we know that there is no carry over from column 3 from the right.
N + R = 10 + E => 1 + E + R = 10 + E => R = 9, impossible, as S=9
or 1 + N + R = 10 + E => 1 + 1 + E + R = 10 + E => R = 8
And there is a carry over from the column 1 from the right, so:
Y cannot be 0 or 1, as already used so D + E > 11
8 and 9 are already taken so we could have 7 + 5 = 12, 7 + 6 = 13 and that's it.
It means that E is 7 or D is 7.
If E is 7 then E+1=9=N, impossible, so D = 7
Then, E is 5 or 6
if E = 6 E + 1 = N = 7, impossible, so E = 5 and N = 6.
And 7 + 5 = 12 so Y = 2.
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
odd function definition
A sample of 55 chewable vitamin tablets have a sample mean of 249 milligrams of vitamin C. Nutritionists want to perform a hypothesis test to determine how strong the evidence is that the mean mass of vitamin C per tablet differs from 248 milligrams. State the appropriate null and alternate hypotheses.
Answer:
Step-by-step explanation:
The null hypothesis is mostly of the time the default hypothesis while the alternative hypothesis is the opposite of the null hypothesis and always tested against the null.
In this case study, the null hypothesis is: mean mass of vitamin c tab = to 248 milligrams
The alternative hypothesis is: mean mass of vitamin c tab =/ 248 milligrams
Why 200/3 doesn’t work
Answer:
it does work
i think u mean why is it not whole
but it is not a whole number
Step-by-step explanation:
200/3=66.6(6 is repeating)
for example if u have 200 chocolates and u give them to 3 people
everyone will have 66
and u will have 2 left
2/3 is also 0.66(6 repeating)
66+0.66(6repeating)
=66.66(6repeating0
HOPE I HELPED
PLS MARK BRAINLIEST
DESPERATELY TRYING TO LEVEL UP
-ZYLYNN JADE ARDENNE
Answer:
Step-by-step explanation:
it does not work as a whole number.
but it does work in simple division with fraction.
200 / 3 = 66 and [tex]\frac{2}{3}[/tex]
Kara Danvers (Supergirl) has always relied on her strength to win fights. But what happens when she meets an alien just as strong? Her sister is training her to be a more technical fighter so that Supergirl can meet any challenge. The data below record the significant strikes during randomly selected training sessions 6 months apart. Is Kara showing improvement in her fighting?
Answer:
The answer is below
Step-by-step explanation:
The corresponding data are missing, which are the following:
Strikes (pre):
29
32
44
34
19
Strikes (post):
51
45
68
92
64
We have to say the difference between the post-pre values of the strike. The d will be the average of the differences between the post and pre values. If Kara is to show improvement, her post-workout attacks should be more than the pre-workout values. Let m be the population mean of the difference:
H0: m = 0 the mean difference in Strikes between post and pre is zero.
H0: m>0, the mean difference in strikes between post and pre is more than zero.
Complete the statement.
Answer:
VY
Step-by-step explanation:
Coz they all look the same on the sides
If x = 2, y = 8, find (i) x³+y³ (ii) ∛y
Answer:
(i) 520
(ii) 2
Step-by-step explanation:
(i) x³ + y³
Plug x as 2, and y as 8.
(2)³ + (8)³
Solve for exponents.
8 + 512
Add.
= 520
(ii) ∛y
Plug y as 8.
∛(8)
Solve for cube root.
= 2
Answer:
( i ) 520
( ii ) 2
Step-by-step explanation:
We can find this solution by plugging in known values -
If x = 2, y = 8
x³+y³ = ( 2 )³ + ( 8 )³ = 8 + 512
= 520
Know let us move on to the second half -
We only need one part of this information now, y = 8. If so,
∛y = ∛8
2 x 2 x 2 = 8 - and thus 2 should be our solution for this portion.
How do I do this? I need the correct option
option A is correct answer.
because angle JKL is half of of arc JL .
so, angle JK is equal to 64°.
hope it helps...
What is 86.94 rounded to the nearest tenth
Answer:
86.9
Step-by-step explanation:
Find the number in the tenth place 9 and look one place to the right for the rounding digit 4 Round up if this number is greater than or equal to 5 and round down if it is less than 5
Hope this can help
jake buys a new car for $18,259. each year x after he buys the car, its value y depreciates by $445. which equation models the relationship between x and y?
A. y=445x + 18,259
B. y= -445x + 18,259
C. y= 445x - 18,259
D. y= -445x - 18,259
Answer:
B
Step-by-step explanation:
It can't be A because of the fact that by multiplying 445 by "x" you'll get a higher, postitive number. Meaning that if adding that positive number, you'll get something higher than 18,259. Which isn't our goal. In addition, the key word is "depreciates" which is another word for subtracting. However, that only applies in some circumstances. It can't be D either since you're basically adding a negative number by another negative number. However, "18,259" has to be a positive in this problem. By that you can also eliminate C as well. Meaning that B would be the correct answer.
In the triangle below, what is the length of the hypotenuse?
A. \|3
B. 3\|3
C. 6
D. 3\|2
Answer:
C
Step-by-step explanation:
So you can use the 30, 60, 90 degree triangle ratio of x: 2x: x√3
The 3 is the x, and the hypotenuse is the 2x, so it's 6
Answer:
C. 6
Step-by-step explanation:
I just finished the test and I got 100 percent
If x=-3 is the only x intercept of the graph of a quadrant equation which statement best describes the discriminant of the equation
Complete question:
If x = –3 is the only x-intercept of the graph of a quadratic equation, which statement best describes the discriminant of the equation?
a) The discriminant is negative.
b) The discriminant is –3.
c) The discriminant is 0.
d) The discriminant is positive.
Answer:
c) The discriminant is 0.
Step-by-step explanation:
Here, x = -3 is the only x intercept of graph of a quadrant equation.
In this case the determinant of the quadrant equation will be 0.
i.e, x = 0
The determinant of the quadrant equation will be zero because, since x = -3 is the only x intercept of the graph, the quadrant equation will have equal roots. Also, when there are equal roots in a quadrant equation, the discriminant tends to zero.
Therefore the correct answer is (c) The discriminant is 0.
D = 0
Answer:
C
Step-by-step explanation:
taking the quiz rn
Find the surface area of the attached figure and round your answer to the nearest tenth, if necessary.
Answer:
[tex] S.A = 246.6 in^2 [/tex]
Step-by-step explanation:
The figure given above is a square pyramid, having a square base and 4 triangular faces on the sides that are of the same dimensions.
Surface area of the square pyramid is given as: [tex] B.A + \frac{1}{2}*P*L [/tex]
Where,
B.A = Base Area of the pyramid = 9*9 = 81 in²
P = perimeter of the base = 4(9) = 36 in
L = slant height of pyramid = 9.2 in
Plug in the values into the given formula to find the surface area
[tex] S.A = 81 + \frac{1}{2}*36*9.2 [/tex]
[tex] = 81 + 18*9.2 [/tex]
[tex] = 81 + 165.6 [/tex]
[tex] S.A = 246.6 in^2 [/tex]
Multiply (2.0 ⋅ 10−4) ⋅ (3.1 ⋅ 10−20). Express the answer in scientific notation. 6.2 ⋅ 10−80 6.2 ⋅ 10−24 6.2 ⋅ 1024 6.2 ⋅ 1080
Answer:
6.2* 10 ^-24
Step-by-step explanation:
(2.0 ⋅ 10−4) ⋅ (3.1 ⋅ 10−20)
Multiply the numbers
2.0 * 3.1 =6.2
Add the exponents
10 ^-4 * 10 ^-20 = 10 ^( -4+-20) = 10 ^ -24
Put back together
6.2* 10 ^-24
The number is in scientific notation since there is one nonzero digit in front of the decimal
Answer:
B, now give the other person brainlist
The jogging track is of a mile long. If Ashley jogged around it 4 times, how far did she run?
Answer: 4 miles
Step-by-step explanation:
If Ashley ran 1 mile 4 times, she ran 1+1+1+1, or 1*4, or 4 miles.
Hope it helps <3
Determine the measure of the unknown variables
Answer:
27°Step-by-step explanation:
Let's create an equation:
[tex]5y = 135[/tex]
( Being vertically opposite angles)
Now, let's solve
Divide both sides of the equation by 5
[tex] \frac{5y}{5} = \frac{135}{5} [/tex]
Calculate
[tex] y = 27[/tex]
Hope this helps...
Best regards!!
Write an equation and then solve each word problem: My computer can download a movie in 5 hours. If I install an extra processor it can download the movie in 4 hours. How long, working alone, would it have taken the new extra processor to download the movie? Pls help me within 10 minutes
Answer:
The new extra processor would take 20 hours to download the movie.
Step-by-step explanation:
This word problem presents two variables: [tex]n[/tex] - Processing capacity, dimensionless; [tex]t[/tex] - Download time, measured in hours. Both variables exhibit a relationship of inverse proportionality, that is:
[tex]t \propto \frac{1}{n}[/tex]
[tex]t = \frac{k}{n}[/tex]
Where [tex]k[/tex] is the proportionality constant.
Now, let suppose that original processor has a capacity of 1 ([tex]n = 1[/tex]), the proportionality constant is: ([tex]t = 5\,h[/tex])
[tex]k = n\cdot t[/tex]
[tex]k = (1)\cdot (5\,h)[/tex]
[tex]k = 5\,h[/tex]
The equation is [tex]t = \frac{5}{n}[/tex] and if time is reduced to 4 hours by adding an extra processor, the processing capacity associated with this operation is: ([tex]t = 4\,h[/tex])
[tex]n = \frac{5}{t}[/tex]
[tex]n = \frac{5\,h}{4\,h}[/tex]
[tex]n = 1.25[/tex]
Then, the extra processor has a capacity of 0.25. The time required for the new extra processor to download the movie is: ([tex]n = 0.25[/tex])
[tex]t = \frac{5\,h}{0.25}[/tex]
[tex]t = 20\,h[/tex]
The new extra processor would take 20 hours to download the movie.
21% of deaths among male adults can be attributed to heart diseases. Is this percentage different among residents in Sonoma County? State the Null and Alternative hypothses
Answer:
Step-by-step explanation:
The null hypothesis is usually the default statement while the alternative hypothesis is its opposite and usually tested against the null hypothesis.
In this case study, the null hypothesis is u = 21%/0.21, the percentage is not different among residents in Sonoma County and is equal to 0.21.
While the alternative hypothesis is u =/ 0.21, the percentage is different among residents in Sonoma County; not equal to 0.21
Helen has 48 cubic inches of clay to make a solid
square right pyramid with a base edge measuring 6
inches.
Which is the slant height of the pyramid if Helen uses all
the clay?
O 3 inches
O4 inches
O 5 inches
O 6 inches
6 in
Save and Exit
Next
Submit
Mark this and return
Answer:
4 inches.
Step-by-step explanation:
The formula for the volume of a pyramid is v=1/3bh.
V is the volume of the shape
1/3 is just a rational number or fraction.
b is the area of the base shape of the 3d shape
h is the height of the shape (slant height).
The general formula for the volume of all shapes is V=Bh
V is the volume
B is the area of the base
h is the height of the prism.
In this case, we have a pyramid, so let's use the formula V=1/3Bh.
We know what the volume so 48=?
We can put 1/3 so 48=1/2 times ? times ?.
The base shape of this pyramid is a square, and it has an edge of 6 inches. We need to find the area of that square because it is the area of our base. the formula for finding the area of a square is A=S squared.
A is the area of the shape
S is the side length.
The reason why it is squared is because all sides of a square are equal to each other. Since the base edge is 6 inches, the other edges are 6 inches as well. There are 4 edges in a square.
A= 6 times 6.
A=36.
We have the area of the base, so we can put 48=1/3 times 36 times ?.
We are finding what the slant height is, so let's put the letter "h" to represent the slant height.
Now, 48=1/3 times 36 times h.
All we have to do is solve for h.
First we have to simplify one side of the equation.
To simplify, we have to do 1/3 times 36, or you can do 36 divided by 3. It is your choice. 36 divided by 3 is 12.
Now we have 12h=48.
Isolate h by dividing both sides by 12. 12h divided 12 is h. 48 divided by 12 is 4.
Therefore h=4 inches. The reason we divide both sides is because we have to do the inverse operation of the original equation. For instance 12h=48. To get to 48, you do 12 times h. We take the inverse (opposite) operation of multiplication (division). That will isolate for h.
The slant height of this square pyramid is 4 inches.
Hope this helps. Have a good rest of your day!
The slant height of the pyramid is 4 inches. Therefore, the option B is the correct answer.
What is the volume?Volume is the measure of the capacity that an object holds.
Formula to find the volume of the object is Volume = Area of a base × Height.
Given that, volume of square right pyramid = 48 cubic inches and base edge measuring 6 inches.
We know that, the volume of square based pyramid =a²h/3.
Here, a=6 inches and h=slant height
Now, 48= (6²×h)/3
48=36h/3
48=12h
h=4 inches
Therefore, the option B is the correct answer.
To learn more about the volume visit:
https://brainly.com/question/13338592.
#SPJ7
Find the Surface area of the attached image and round answer to the nearest tenth, if necessary.
Answer:
150 m²
Step-by-step explanation:
area of triangle is 1/2(6)(9.5) = 28.5
there are 4 triangles
28.5 x 4 = 114
bottom is 6 x 6 = 36
114 + 36 = 150 m²
What is the solution, if any, to the inequality |3x|≥0?
Answer:
Infinitely many solutions
Step-by-step explanation:
Any value of x will make this inequality true, hence there are infinitely many solutions. Another way to say this is True for all x on the interval [-infinite,+infinite]
The reason this is true, is because all values of an absolute value will be greater than or equal to 0.
Cheers.
That's weird !
X is ANY NUMBER !
-∞ ≤ X ≤ ∞
Use the Limit Comparison Test to determine whether the series converges.
[infinity]∑ from k = 1 StartFraction 8/k StartRoot k + 7 EndRoot EndFraction
Answer:
The infinite series [tex]\displaystyle \sum\limits_{k = 1}^{\infty} \frac{8/k}{\sqrt{k + 7}}[/tex] indeed converges.
Step-by-step explanation:
The limit comparison test for infinite series of positive terms compares the convergence of an infinite sequence (where all terms are greater than zero) to that of a similar-looking and better-known sequence (for example, a power series.)
For example, assume that it is known whether [tex]\displaystyle \sum\limits_{k = 1}^{\infty} b_k[/tex] converges or not. Compute the following limit to study whether [tex]\displaystyle \sum\limits_{k = 1}^{\infty} a_k[/tex] converges:
[tex]\displaystyle \lim\limits_{k \to \infty} \frac{a_k}{b_k}\; \begin{tabular}{l}\\ $\leftarrow$ Series whose convergence is known\end{tabular}[/tex].
If that limit is a finite positive number, then the convergence of the these two series are supposed to be the same.If that limit is equal to zero while [tex]a_k[/tex] converges, then [tex]b_k[/tex] is supposed to converge, as well.If that limit approaches infinity while [tex]a_k[/tex] does not converge, then [tex]b_k[/tex] won't converge, either.Let [tex]a_k[/tex] denote each term of this infinite Rewrite the infinite sequence in this question:
[tex]\begin{aligned}a_k &= \frac{8/k}{\sqrt{k + 7}}\\ &= \frac{8}{k\cdot \sqrt{k + 7}} = \frac{8}{\sqrt{k^2\, (k + 7)}} = \frac{8}{\sqrt{k^3 + 7\, k^2}} \end{aligned}[/tex].
Compare that to the power series [tex]\displaystyle \sum\limits_{k = 1}^{\infty} b_k[/tex] where [tex]\displaystyle b_k = \frac{1}{\sqrt{k^3}} = \frac{1}{k^{3/2}} = k^{-3/2}[/tex]. Note that this
Verify that all terms of [tex]a_k[/tex] are indeed greater than zero. Apply the limit comparison test:
[tex]\begin{aligned}& \lim\limits_{k \to \infty} \frac{a_k}{b_k}\; \begin{tabular}{l}\\ $\leftarrow$ Series whose convergence is known\end{tabular}\\ &= \lim\limits_{k \to \infty} \frac{\displaystyle \frac{8}{\sqrt{k^3 + 7\, k^2}}}{\displaystyle \frac{1}{{\sqrt{k^3}}}}\\ &= 8\left(\lim\limits_{k \to \infty} \sqrt{\frac{k^3}{k^3 + 7\, k^2}}\right) = 8\left(\lim\limits_{k \to \infty} \sqrt{\frac{1}{\displaystyle 1 + (7/k)}}\right)\end{aligned}[/tex].
Note, that both the square root function and fractions are continuous over all real numbers. Therefore, it is possible to move the limit inside these two functions. That is:
[tex]\begin{aligned}& \lim\limits_{k \to \infty} \frac{a_k}{b_k}\\ &= \cdots \\ &= 8\left(\lim\limits_{k \to \infty} \sqrt{\frac{1}{\displaystyle 1 + (7/k)}}\right)\\ &= 8\left(\sqrt{\frac{1}{\displaystyle 1 + \lim\limits_{k \to \infty} (7/k)}}\right) \\ &= 8\left(\sqrt{\frac{1}{1 + 0}}\right) \\ &= 8 \end{aligned}[/tex].
Because the limit of this ratio is a finite positive number, it can be concluded that the convergence of [tex]\displaystyle a_k &= \frac{8/k}{\sqrt{k + 7}}[/tex] and [tex]\displaystyle b_k = \frac{1}{\sqrt{k^3}}[/tex] are the same. Because the power series [tex]\displaystyle \sum\limits_{k = 1}^{\infty} b_k[/tex] converges, (by the limit comparison test) the infinite series [tex]\displaystyle \sum\limits_{k = 1}^{\infty} a_k[/tex] should also converge.