A large stockpile of used pumps contains 20% that are currently unusable and need to be repaired. A repairman is sent to the stockpile with three repair kits. He selects pumps at random and tests them one at a time. If a pump works, he goes on to the next one. If a pump doesn't work, he uses one of his repair kits on it. Suppose that it takes 10 minutes to test whether a pump works, and 20 minutes to repair a pump that does not work. The expected value and variance of the total time it takes the repairman to use up his three kits are, respectively:____.

Answer:

Expected value = 190

Variance = 4000

Step-by-step explanation:

Let X be the number of the trials until the third success of the bad pump.

This implies that X is a negative binomial distribution having θ = 20% = 0.2.

Now, if for example it will take X trials to use up the three pumps, then the total time is 10 min/trials + extra 10 minutes for the 3 bad pumps

This means the total time is written as;

T = 10X + (10 + 10 + 20)

T = 10X + 40

Mean which is also expected value of X is;

μ_x = 3/0.2 = 15

Variance of X is; σ²_x = 40

Thus;

Mean of T will be;

μ_T = 10μ_x + 40

μ_T = 10(15) + 40

μ_T = 190

Also, variance of T will be;

σ²_T = 10²•σ²_x

σ²_T = 100 × 40

σ²_T = 4000

PLEASE ANSWER OFFERING BRAINLEST

Triangle MNQ is similar to triangle MLP. Determine the length of LP.

a. 2 inches
b. 9 inches
c. 12 inches
d. 16 inches

A bus travels 20 km in 30 minutes. What is the average speed of the
bus in km/hr?

Answer this question

Identify the property: 6m + 2p = 2p + 6m

A: Assocciative
B: Communitave
C: Distributive
D: Identity

if you divide a positive by positive, do you get a negative or another positive?

A car travels 195 miles from his starting point in three hours if the car continues at the same average pay for another five hours how far away I have trouble from the starting point

87
Solve for x.
x = 64
O A
-4,4
OB.
-8,8
OC.
-32, 32
D.
-64, 64
HELP AGAIN

how long of a chain Can Jill make by attaching a 13 3/4 inch chain to a 15 2/4 in chain?​

< Back
Record: 0/3 Score: o Penalty: None
Give Up
Show Example
Complete se
Dylan Smart
Quadratic Word Problems
Feb 24,9:01:16 PM
Watch help video
?.
When 18 is subtracted from the square of a number, the result is 3 times
the number. Find the negative solution.

Enter a number in the space provided to make the equation true.

Josh has 4 boxes of candy to share with his 20 classmates. If each classmate receives the same amount of candy, how much candy should each classmate get? Your answer​

-
Which expression is equivalent to 3x+10-x+12

Diego makes 6 anklets. Each anklets uses 9 inches of string. How many inches of string does Diego us?

Simplify.


−y − 7x + 6y


The simplified expression is

The radius of circle L is 22cm what is the lenght of its diameter ?
A. 88cm
B. 44 cm
C. 22cm
D. 11cm

Sienna has graphed the equation y - 3x = -2
on the coordinate plane below. Next, she will graph the
equation y = 3x 2 on the same coordinate plane.
Determine whet
y
A
Select True or Fals
6
The system of ed
4
2
The system of ec

does 2m, 2m, 4m make a triangle?

A salesman makes both a base salary and also a commission, which is a percentage of
what he sells. Each month, if his sales total s dollars, he makes a total of 5000+ 0.2s. What
does the 5000 represent?

What is the domain of the function

Add or subtract. Express in simplest form. 6 over 7 +(-5 over 14)

!!!!!!!!!!!!!!!!!!!!!

The area of a rectangle is 84 inches. It has a length of x−2 and a width of x+3. What are the dimensions of the rectangle?

−12 inches by −7 inches

7 inches by 12 inches

−11 inches and −6 inches

8 inches by 13 inches

5 kilometers in numbers

A local pizza shop sells pizza by the slice at a price of $1.25 per each slice. The table below represents how much it would cost for different amounts of slices. What is the SLOPE of this table?

Slices (x) Total Cost (y)
0 slices $0
1 slice $1.25
2 slices $2.50
4 Slices $5
6 slices $7.50
8 slices $10

Work out the area of the triangle 5 cm and 12 cm

Help plz I will give you BRAINLYST I don't know if I spelled that right lol but plz and I will give you a follow!?!?!?!?


The value of 34 + 5 ⋅ 5 = ___.

Which of the exponential growth functions has a multiplicative rate of change of 4? A 2-column table has 4 rows. The first column is labeled x with entries negative 1, 0, 1, 2. The second column is labeled f (x) with entries one-half, 1, 2, 4. A 2-column table has 4 rows. The first column is labeled x with entries negative 1, 0, 1, 2. The second column is labeled f (x) with entries one-eighth, 1, 8, 64. A 2-column table has 4 rows. The first column is labeled x with entries negative 1, 0, 1, 2. The second column is labeled f (x) with entries one-fourth, 1, 4, 16.

graph 4x minus 2y equals 10

how does 9+10 equal 21?​

When asked about their favorite
holiday, only 10% of the class picked
Valentines Day. How many student
picked Valentine's Day if there were 30
students?

find the value of x. (geometry)