Answer:
Following are the answer to this question:
Step-by-step explanation:
The principle vale of Arg(3)
[tex]Arg(3)=-\pi+\tan^{-1} (\frac{|Y|}{|x|})[/tex]
The principle value of the [tex]\logi= \log(0+i)\ \ \ \ \ _{where} \ \ \ x=0 \ \ y=1> 0[/tex]
So, the principle value:
a)
[tex]\to \log(i)=\log |i|+i Arg(i)\\\\[/tex]
[tex]=\log \sqrt{0+1}+i \tan^{-1}(\frac{1}{0})\\\=\log 1 +i \tan^{-1}(\infty)\\\=0+i\frac{\pi}{2}\\\=i\frac{\pi}{2}[/tex]
b)
[tex]\to \log(-i)= \log(0-i ) \ \ \ x=0 \ \ \ y= -1<0\\[/tex]
Principle value:
[tex]\to \log(-i)= \log|-i|+iArg(-i) \\\\[/tex]
[tex]=\log \sqrt{0+1}+i(-\pi+\tan^{-1}(\infty))\\\\=\log1 + i(-\pi+\frac{\pi}{2})\\\\=-i\frac{\pi}{2}[/tex]
c)
[tex]\to \log(-1+i) \ \ \ \ x=-1, _{and} y=1 \ \ \ x<0 and y>0[/tex]
The principle value:
[tex]\to \log(-1+i)=\log |-1+i| + i Arg(-1+i)[/tex]
[tex]=\log \sqrt{1+1}+i(\pi+\tan^{-1}(\frac{1}{1}))\\\\=\log \sqrt{2} + i(\pi-\tan^{-1}\frac{\pi}{4})\\\\=\log \sqrt{2} + i\tan^{-1}\frac{3\pi}{4}\\\\[/tex]
d)
[tex]\to i^i=w\\\\w=e^{i\log i}[/tex]
The principle value:
[tex]\to \log i=i\frac{\pi}{2}\\\\\to w=e^{i(i \frac{\pi}{2})}\\\\=e^{-\frac{\pi}{2}}[/tex]
e)
[tex]\to (-i)^i\\\to w=(-i)^i\\\\w=e^{i \log (-i)}[/tex]
In this we calculate the principle value from b:
so, the final value is [tex]e^{\frac{\pi}{2}}[/tex]
f)
[tex]\to -1^i\\\\\to w=e^{i log(-1)}\\\\\ principle \ value: \\\\\to \log(-1)= \log |-1|+iArg(-i)[/tex]
[tex]=\log \sqrt{1} + i(\pi-\tan^{-1}\frac{0}{-1})\\\\=\log \sqrt{1} + i(\pi-0)\\\\=\log \sqrt{1} + i\pi\\\\=0+i\pi\\=i\pi[/tex]
and the principle value of w is = [tex]e^{\pi}[/tex]
g)
[tex]\to -1^{-i}\\\\\to w=e^(-i \log (-1))\\\\[/tex]
from the point f the principle value is:
[tex]\to \log(-1)= i\pi\\\to w= e^{-i(i\pi)}\\\\\to w=e^{\pi}[/tex]
h)
[tex]\to \log(-1-i)\\\\\ Here x=-1 ,<0 \ \ y=-1<0\\\\ \ principle \ value \ is:\\\\ \to \log(-1-i)=\log\sqrt{1+1}+i(-\pi+\tan^{-1}(1))[/tex]
[tex]=\log\sqrt{2}+i(-\pi+\frac{\pi}{4})\\\\=\log\sqrt{2}+i(-\frac{3\pi}{4})\\\\=\log\sqrt{2}-i\frac{3\pi}{4})\\[/tex]
Consider the following scores. (i) a score of 40 from a distribution with mean 50 and standard deviation 10 (ii) a score of 45 from a distribution with mean 50 and standard deviation 5 How do the two scores compare relative to their respective distributions
Answer:
The scores are equal
Step-by-step explanation:
The z-score for any normal distribution is:
[tex]z=\frac{X-\mu}{\sigma}[/tex]
(i) Score (X) = 40
Mean (μ)= 50
Standard deviation (σ) = 10
[tex]z=\frac{40-50}{10}\\ z=-1[/tex]
(ii) Score (X) = 45
Mean (μ)= 50
Standard deviation (σ) = 5
[tex]z=\frac{45-50}{5}\\ z=-1[/tex]
Both scores have the same z-score, which means that, relative to their respective distributions, the scores are equal.
Which of the following shapes can NOT be created by revolving a two-dimensional figure around an axis? There can be more than 1. A. come B. cube C. Rectangular pyramid D. Rectangular Prism E. Cylinder F. Sphere
PLEASE HELP
Answer:
A. Cone
D. Rectangular Prism
E. Cylinder
F. Sphere
Step-by-step explanation:
Rectangular Prism is a solid three dimensional shape. It has six faces which are sides of a rectangle. It is also known as Cuboid. The rectangular prism cannot be formed with two dimensional shapes. Sphere is a geometrical object which is a three dimensional circle. This shape has a circumference so this shape cannot be formed with two dimensional shapes.
Select the correct solution set.
x + 17 ≤ -3
A.{x | x ≤ 14}
B.{x | x ≤ -20}
C.{x | x ≥ -20}
A tower is 40 ft tall and 20 ft wide. A model of the tower is 5 in. tall. Identify the width of the model in inches.
Answer:
The width of the model will be 2.5 inches
Step-by-step explanation:
The tower was scaled down by a factor to a smaller size in the model. We are to, first of all, determine this factor and then use it to scale down the width of the model.
Step One: Determine the scale factor from the tower height.
The scale factor is obtained from the formula:
Scale factor = model size / observed size
This will be
Height of model tower/ height of the real tower.
The height of the model tower is 5 inches which is the same as 0.416667 ft
Scale factor = 0.416667 ft/ 40ft = 0.0104
Step two: Multiply the width of the real-life tower by the scale factor to get the model width.
Width of model =20ft X 0.0104 = 0.208ft
Step three: Convert your answer back to inches.
We will now have to convert 0.208 ft back to inches by multiplying by 12
This will be 0.208 X 12 =2.5 inches.
The width of the model will be 2.5 inches
The Fine Line Pen Company makes two types of ballpoint pens: a silver model and a gold model. The silver model requires 1 minute in a grinder and 3 minutes in a bonder. The gold model requires 3 minutes in a grinder and 4 minutes in a bonder. Because of maintenance procedures, the grinder can be operated no more than 30 hours per week and the bonder no more than 50 hours per week. The company makes $5 on each silver pen and $7 on each gold pen. How many of each type of pen should be produced and sold each week to maximize profits?
Answer:
Optimal production = 600 gold pens
Revenue = 600*7 = $4200 gold pens
Step-by-step explanation:
The Fine Line Pen Company makes two types of ballpoint pens: a silver model and a gold model.
A. The silver model requires 1 minute in a grinder and 3 minutes in a bonder.
B. The gold model requires 3 minutes in a grinder and 4 minutes in a bonder.
Because of maintenance procedures,
C. the grinder can be operated no more than 30 hours per week and
D. the bonder no more than 50 hours per week.
The company makes
E. $5 on each silver pen and
F. $7 on each gold pen.
How many of each type of pen should be produced and sold each week to maximize profits?
Solution:
We will solve the problem graphically, with number of silver pens, x, on the x axis, and number of gold pens, y, on the y axis, i.e.
1. From A and C, the maximum number of silver pens
x <= 30*60 / 1 = 1800 and
x <= 50*60 /3 = 1000 ....................(1) bonder governs
2. from A & D, the maximum number of gold pens
y <= 30*60 / 3 = 600 .....................(2) grinder governs
y <= 50*60 / 4 = 750
3. From D,
x + 3y <= 30*60 = 1800 ...................(limit of grinder) ..... (3)
3x + 4y <= 50*60 = 3000 .................(limit of bonder) .......(4)
Need to maximize profit,
Z(x,y) = 5x+7y, represented by parallel lines y = -5x/7 + k such that all constraints of (3) and (4) are satisfied.
The maximum is obtained when Z passes through (360,480), i.e. at intersection of constraints (3) and (4). Using slope intercept form,
(y-480) = -(5/7)(x-360)
or y=-(5/7)x + (737+1/7) [the purple line] which violates the red line, so not a solution.
Next try the point (0,600)
(y-600) = -(5/7)(x-0), or
y = 600 - (5/7)x [the black line]
As we can see all point on the black (in the first quadrant) satisfy the constraints, so it is a feasible solution, and is the optimal solution, with a revenue of
Revenue = 600*7 = 4200 gold pens
The perimeter of an equilateral triangle with a side length of 12 units is:
Answer:
Hey there!
An equilateral triangle has all sides equal to each other, so the perimeter would be 3x, where x is the length of one side.
Thus, the perimeter for this equilateral triangle would be 3(12)=36
Hope this helps :)
Answer:
[tex]\boxed{Perimeter = 36 \ units}[/tex]
Step-by-step explanation:
Perimeter = sum of all sides
Perimeter = 12 +12 + 12
Perimeter = 36 units
Next number in this series is? 2 2 1/2 1 1/2 2
First, let's figure out the pattern that this series follows. We can see that the first number is increased by 1/2 to get to 2 1/2. Then, the second number is decreased by 1 to get to 1 1/2. Finally, the pattern repeats.
So, let's apply this pattern to find the next number in this series.
2, 2 1/2, 1 1/2, 2, 1
The next number in this series is 1.
Hope this helps!! :)
a sample of bacteria is growing at an hourly rate of 14% according to the exponential growth function.the sa
Answer:
pleasse elaborate more
Step-by-step explanation:
Determine the convergence or divergence of the sequence with the given nth term. If the sequence converges, find its limit. (If the quantity diverges, enter DIVERGES.) an = (n − 2)! n!
Answer: Diverging
Step-by-step explanation:
Find explanations in the attached file
What's the common denominator of this equation?
3 - b = 6-7
Answer:
b = 4
Step-by-step explanation:
3 - b = 6 - 7
3 - b = -1
-b = -1 -3
-b = -4
b = 4
What is the solution to the system of equations? y = –3x + 6 y = 9
PLEASE PLEASE PLEASE HELP
Answer:
1) 18
2) P
Step-by-step explanation:
1) Multiply the top number by itself and then reverse the digits!
9*9 = 81 reversed is 18
2) Seems to be the number of line ends a letter has when you write it down. P only has one end, at the bottom.
Answer:
P
Step-by-step explanation:
2.
The number of strokes of the letter that come to an end.
The bottom of the A has two sticks that come to an end.
A = 2
The B has no sticks coming to an end.
B = 0
The C and an upper and a lower stroke coming to an end.
C = 2
D has none.
D = 0
E has 3 sticks coming to an end.
E = 3
etc.
M has 3.
N has 2.
O has 0.
P has 1 stick coming to an end.
Q has none.
R has 2.
S has 2.
T has 3.
U has 2.
V has 2.
W has 3.
X has 4.
Y has 3
Z has 2.
Of all letters after L, only P has exactly 1 stroke coming to an end.
Answer: P
Please help with 4d.
Answer:
(Hemingway, The Old Man and the Sea)(Orwell, 1984)Step-by-step explanation:
A short web search will turn up the authors of the given titles:
The Old Man and the Sea - Hemingway
Huckleberry Finn - Twain
Moby D.ick - Melville
1984 - Orwell
Crime and Punishment - Dostoevsky
Evaluate the determinant for the following matrix 1, 4, 4, 5, 2, 2, 1, 5, 5
Answer:
0
Step-by-step explanation:
The determinant of this matrix is zero (0).
Where L is the length, in feet, of the pendulum, and π is approximately 22/7. How long must the pendulum be if one complete cycle takes 8 seconds?
Answer:
The simple pendulum should be 15.9 m long.
Step-by-step explanation:
Approximately (for small amplitudes), the period of a simple pendulum is
T = 2*pi * sqrt (L/g), L=length
using pi = 22/7, and g=9.8 m/s^2
8 = 2* 22/7 * sqrt(L/9.8)
solve for L
L = (8*7/(2*22))^2 * 9.8
= 15.874 m
That's quite a long pendulum!
"Smokers are much more likely to speed, run red lights, and get involved in car accidents than nonsmokers."(a) Can you think of reasons why this statement might be misleading?(b) Can you suggest a causal link between smoking and car accidents?
Answer: Smokers pay less attention to driving while trying to light a cigarette.
Step-by-step explanation:
( A ) reasons for, why the given statement was misleading.
Following are the reasons for accidents
(i) Drunk Driving.
(ii) Driving during the night.
(iii) Smoking.
(iv) Unsafe lane changes.
(v) Driving the wrong way.
(vi) Bad weather e.g fog.
From the list above, it is shown that, smoking is also one of the major cause of car accidents on the roads.
( B.) Smokers tends to pay less attention to driving why trying to light a cigarette.
Find the value of annuity if the periodic deposit is $1500 at 8% compounded semiannually for 22 years
Answer:
The value of annuity is [tex]P_v = \$ 32058[/tex]
Step-by-step explanation:
From the question we are told that
The periodic payment is [tex]P = \$ 1500[/tex]
The interest rate is [tex]r = 8\% = 0.08[/tex]
Frequency at which it occurs in a year is n = 2 (semi-annually )
The number of years is [tex]t = 22 \ years[/tex]
The value of the annuity is mathematically represented as
[tex]P_v = P * [1 - (1 + \frac{r}{n} )^{-t * n} ] * [\frac{(1 + \frac{r}{n} )}{ \frac{r}{n} } ][/tex](reference EDUCBA website)
substituting values
[tex]P_v = 1500 * [1 - (1 + \frac{0.08}{2} )^{-22 * 2} ] * [\frac{(1 + \frac{0.08}{2} )}{ \frac{0.08}{2} } ][/tex]
[tex]P_v = 1500 * [1 - (1.04 )^{-44} ] * [\frac{(1.04 )}{0.04} ][/tex]
[tex]P_v = 1500 * [1 - 0.178 ] * [\frac{(1.04 )}{0.04} ][/tex]
[tex]P_v = \$ 32058[/tex]
For the functions f(x)=x4−x3−7x2+9x−2 and g(x)=x−1, find (f/g)(x) and (f/g)(2).
Answer:
[tex](f/g)(x)=\frac{x^4-x^3-7x^2+9x-2}{x-1} =x^3-7x+2\,\,\,for\,\,x\neq 1[/tex]
[tex](f/g)(2)=-4[/tex]
Step-by-step explanation:
[tex](f/g)(x)=\frac{x^4-x^3-7x^2+9x-2}{x-1} =x^3-7x+2\,\,\,for\,\,x\neq 1[/tex] and undefined for x = 1.
Notice that (x-1) is in fact a factor of f(x), so the quotient of the two functions introduces a "hole" for the new function at x = 1.
f(2) can be found by simply evaluating the expression for x = 2:
[tex](f/g)(2)=2^3-7(2)+2=-4[/tex]
Which of the following are solutions to the equation below?
Check all that apply.
x2 - 6x + 9 = 11
Answer:
x = 3 ± sqrt(11)
Step-by-step explanation:
x^2 - 6x + 9 = 11
Recognizing that this is a perfect square trinomial
(x-3) ^2 =11
Taking the square root of each side
sqrt((x-3) ^2) = ± sqrt(11)
x-3 =± sqrt(11)
Add 3 to each side
x = 3 ± sqrt(11)
Answer:
[tex]\large\boxed{\sf \ \ x = 3+\sqrt{11} \ \ or \ \ x = 3-\sqrt{11} \ \ }[/tex]
Step-by-step explanation:
Hello,
[tex]x^2-6x+9=11\\<=> x^2-2*3*x+3^2=11\\<=>(x-3)^2=11\\<=> x-3=\sqrt{11} \ or \ x-3=-\sqrt{11}\\<=> x = 3+\sqrt{11} \ or \ x = 3-\sqrt{11}[/tex]
Do not hesitate if you have any question
Hope this helps
find the product of .42 and 7/20
To make it easier, you can convert 7/20 to a decimal, and as a decimal it is 0.35. 0.42*0.35=0.147, so .42*7/20=0.147.
Answer:
0.147
Step-by-step explanation:
0.42 * 7/20
Well, 0.42 = 42/100. Now we have both numbers as fractions.
We can simplify 42/100 to 21/50
Therefore we have 7/20 * 21/50
To multiply fractions multiply the numerators together and multiply the denominators together.
This gives: 147 / 1000
Which is equal to 0.147
Therefore 0.42 * 7/20 = 0.147
Triangle ABC, with vertices A (3,0), B (2,4), and C (4,2)undergoes a transformation to form triangle ABC with vertices A(3.0), B (2, -4) and C(4, -2). this type of transformation that triangle ABC undegoes is a ___________. If triangle ABC undergoes a transformation to form triangle A"B"C" with vertices A(-3.0) B(-2, -4) and C(-4, -2), then the typeof transformation that triangle A'B'C' undergoes is a ____________.
Answer:
1st blank: X axis reflection
2nd blank: Y axis reflection
Step-by-step explanation:
If you drew the first triangle and then the second triangle on a piece of paper, you would notice that it would reflect across the corresponding axis.
So the solution is to just draw it out.
Answer:
reflection across the x axis and the second is a reflection across the y axis.
Suppose Mr. Pink is 28 years old right now and puts away $1,800 per quarter in an account that returns 6% interest. a.) How much will be in the account when he turns 68? b.)What is his total contribution to the account?
Answer: (a) When he turns 68 , the account will have = $1,179,415.39
(b) $ 288,000
Step-by-step explanation:
Formula: Future value of annuity =[tex]P[\dfrac{(1+r)^n-1}{r}][/tex], where P+ periodic payment, r = rate of interest per period, n= number of periods.
As per given, we have
P= $1800
rate of interest = 6% = 0.06
(a) n= 68-28 = 40
Rate per period : r= [tex]\dfrac{0.06}{4}=0.015[/tex]
Number of periods: n = 4x 40 =160
Now, Future value of amount when Mr. Pink turns 28 years = [tex]1800(\dfrac{(1+0.015)^{160}-1}{0.015})[/tex]
[tex]=1800(\dfrac{10.8284615777-1}{0.015})\\\\=1800\times\dfrac{9.8284615777}{0.015}\\\\\approx\$1179415.39[/tex]
Hence, when he turns 68 , the account will have = $1,179,415.39
(b) Total contribution = P × n
=1800 × 160
=$ 288,000
Hence, Total contribution =$ 288,000
Find the hcf of 15a²b² and -24ab | plzzz solve
Answer:
[tex]\large \boxed{\sf \ \ \ 3\cdot a \cdot b \ \ \ }[/tex]
Step-by-step explanation:
Hello,
First of all, let's find the factors of these two numbers and I will put in boxes the common factors.
[tex]15a^2b^2=\boxed{3}\cdot 5\cdot \boxed{a} \cdot a \cdot \boxed{b} \cdot b \\ \\ \\-24ab=(-1)\cdot 2 \cdot \boxed{3} \cdot 4 \cdot \boxed{a} \cdot \boxed{b}[/tex]
The Highest Common Factor (HCF) is found by finding all common factors and selecting the largest one. So, in this case, it gives
[tex]\large \boxed{\sf \ \ \ 3\cdot a \cdot b \ \ \ }[/tex]
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
Given that a function, g, has a domain of -20 ≤ x ≤ 5 and a range of -5 ≤ g(x) ≤ 45 and that g(0) = -2 and g(-9) = 6, select the statement that could be true for g. A. g(0) = 2 B. g(7) = -1 C. g(-13) = 20 D. g(-4) = -11
Answer:
C. g(-13) = 20
Step-by-step explanation:
Let's check the offered statements:
A. g(0) = 2 . . . . . . doesn't match g(0) = -2
B. g(7) = -1 . . . . . . 7 is not in the domain of g
C. g(-13) = 20 . . . could be true
D. g(-4) = -11 . . . . -11 is not in the range of g
Scores turned in by an amateur golfer at the Bonita Fairways Golf Course in Bonita Springs, Florida, during and are as follows: Season: 7377787674727476 Season: 7069747684797078a. Calculate the mean (to the nearest whole number) and the standard deviation (to decimals) of the golfer's scores, for both years.MeanStandard deviationMeanStandard deviationb. What is the primary difference in performance between and
Complete question is;
Scores turned in by an amateur golfer at the Bonita Fairways Golf Course in Bonita Springs, Florida, during 2005 and 2006 are as follows:
2005 Season: 73 77 78 76 74 72 74 76
2006 Season: 70 69 74 76 84 79 70 78
A) Calculate the mean (to the nearest whole number) and the standard deviation (to decimals) of the golfer's scores, for both years.
B) What is the primary difference in performance between 2005 and 2006? What improvement,
if any, can be seen in the 2006 scores?
Answer:
A) 2006 mean = 75
2005 mean = 75
2006 standard deviation = 5.2644
2005 standard deviation = 2.0702
B)The primary difference is that variation is higher in the 2006 season than the 2005 season.
Step-by-step explanation:
A) Mean is the sum of all scores divided by the number of scores.
Thus;
μ_2005 = (73 + 77 + 78 + 76 + 74 + 72 +74 + 76)/8 = 75
Similarly;
μ_2006 = (70 + 69 + 74 + 76 + 84 + 79 + 70 + 78)/8 = 75
Now, variance is calculated by the sum of the square of mean deviations divided by (n - 1)
Thus;
2005 Variance = ((73-75)² + (77-75)² + (78-75)² + (76-75)² + (74-75)² + (72-75)² + (74-75)² + (76-75)²)/(8-1) = 4.2857
2006 Variance = ((70-75)² + (69-75)² + (74-75)² + (76-75)² + (84-75)² + (79-75)² + (70-75)² + (78-75)²)/(8 - 1) = 27.7143
Now, standard deviation is the square root of variance.
Thus;
2005 standard deviation = √4.2857 = 2.0702
2006 standard deviation = √27.7143 = 5.2644
B) The primary difference is that variation is higher in the 2006 season than the 2005 season.
Also,
Edna transferred a balance of $1400 to a new credit card at the beginning of
the year. The card offered an introductory APR of 2.9% for the first 3 months
and a standard APR of 22.1% thereafter. If the card compounds interest
monthly, which of these expressions represents Edna's balance at the end of
the year? (Assume that Edna will make no payments or new purchases during
the year, and ignore any possible late payment fees.)
Answer:
(1400)(1+0.029/12)3(1+0.221/12)9
Step-by-step explanation:
A p e x
Answer:
Step-by-step explanation:
Just so you know how it looks on the page
HELP PRECALC I DO NOT UNDERSTAND AT ALLLLL!!!!!!!!!!!!!!!!!!!!!!
Answer:
φ ≈ 1.19029 radians (≈ 68.2°)
Step-by-step explanation:
There are simple formulas for A and φ in this conversion, but it can be instructive to see how they are derived.
We want to compare ...
y(t) = Asin(ωt +φ)
to
y(t) = Psin(ωt) +Qcos(ωt)
Using trig identities to expand the first equation, we have ...
y(t) = Asin(ωt)cos(φ) +Acos(ωt)sin(φ)
Matching coefficients with the second equation, we have ...
P = Acos(φ)
Q = Asin(φ)
The ratio of these eliminates A and gives a relation for φ:
Q/P = sin(φ)/cos(φ)
Q/P = tan(φ)
φ = arctan(Q/P) . . . . taking quadrant into account
__
We can also use our equations for P and Q to find A:
P² +Q² = (Acos(φ))² +(Asin(φ))² = A²(cos(φ)² +sin(φ)²) = A²
A = √(P² +Q²)
_____
Here, we want φ.
φ = arctan(Q/P) = arctan(5/2)
φ ≈ 1.19029 . . . radians
A polynomial function is shown below:
f(x) = x3 - 4x2 - x + 4
Which graph best represents the function? (5 points)
Answer:
Simply plug in the polynomial into a graphing calc.
Step-by-step explanation:
Which inequality is shown in this graph?
(0, 2) (-1,-2)
a) y>=-4x+2
b) y>=4x+2
c) y<=-4x+2
d) y<=4x+2
Answer:
B y ≥ 4x + 2
Step-by-step explanation:
1. find slope of the line: (y² - y¹) / (x² - x¹)
(0, 2) and (-1, -2)
(-2 - 2) / (-1 - 0) = -4 / -1 = 4
y = 4x + 2*
*+2 because that is the y-intercept as shown by point (0, 2)
2. the line is solid, therefore the inequality is ≤ or ≥. dashed line would mean < or >
3. the shaded region is on the right side of the line, so the values are greater than. therefore, you use ≥
4. final equation: y ≥ 4x + 2
It took Malik 1 hour and 30 minutes to complete his English essay. He finished the essay at 5:30 pm. What time did he start working on the essay?
Answer:
4:00 pm
Step-by-step explanation:
To find the time it takes Malik to finish his English essay, let's start by subtracting one hour.
5:30 minus 1 hour is 4:30.
Now, subtract 30 minutes.
4:30 minus 30 minutes is 4:00.
Malik started working on his English essay at 4:00 pm.
Hope that helps.