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Ghella [55]
3 years ago
9

A supervisor records the repair cost for 14 randomly selected refrigerators. A sample mean of $79.20 and standard deviation of $

10.41 are subsequently computed. Determine the 90% confidence interval for the mean repair cost for the refrigerators. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.
Mathematics
1 answer:
Nitella [24]3 years ago
5 0

Answer:

( $74.623, $83.777)

The 90% confidence interval is = ( $74.623, $83.777)

Critical value at 90% confidence = 1.645

Step-by-step explanation:

Confidence interval can be defined as a range of values so defined that there is a specified probability that the value of a parameter lies within it.

The confidence interval of a statistical data can be written as.

x+/-zr/√n

Given that;

Mean x = $79.20

Standard deviation r = $10.41

Number of samples n = 14

Confidence interval = 90%

Using the z table;

The critical value that should be used in constructing the confidence interval.

z(α=0.05) = 1.645

Critical value at 90% confidence z = 1.645

Substituting the values we have;

$79.20+/-1.645($10.42/√14)

$79.20+/-1.645($2.782189528308)

$79.20+/-$4.576701774067

$79.20+/-$4.577

( $74.623, $83.777)

The 90% confidence interval is = ( $74.623, $83.777)

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lauren is driving to the grocey store.Tye average distance is d,in miles,she travels over t minutes is giving is givin bu the fu
yulyashka [42]

Answer:

Average distance traveled in 15 minutes = 7.5 miles

Step-by-step explanation:

Given function:

d(t)=0.5t

where d represents average distance traveled in miles and t represents time in minutes traveled.

To find the average distance traveled in t=15 minutes.

Solution:

In order to find the distance traveled in 15 minutes, we will input t=15 in the given function.

d(15)=0.5(15)

d(15)=0.5\times 15

d(15)=7.5 miles

Average distance traveled in 15 minutes = 7.5 miles

4 0
3 years ago
A plumber charges $130 2 hours of work and $235 for 5 hours of workWhat is the of change in dollars per hour
kogti [31]

Answer:

235

Step-by-step explanation:

Figure the rates per hr.

110/3 = 36 2/3

160/5 = 32.

So, the rates are not the same.

Knowing a bit about plumbers, they normally charge a basic fee to just show up, and then they charge per hr.

In cases like these, where we're asked to project to a new data point (in this case an 8-hr job), you should immediately think of a graph. The x-axis would be the hours worked. The y-axis would be the charge for the work (the cost of the job).

We're given two pairs of values:

(3,110) and (5,160).

The next step is to fit a line to them.

y = mx+b is the general equation for a line.

m = the slope = rise/run = change in y / change in x

Call the change in y, dy (for delta y).

Call the change in x, dx (for delta x).

m = dy/dx = 50/2 = 25

The slope is thus 25, which means for each hour, the price goes up by $25. That means the plumber charges $25/hr.

We also know the plumber charges $110 for a 3-hr job. 3*25 = $75. So the base charge would be $110-75 = $35.

y = 25x + 35

Checking this formula at x=3, we know it is 110.

Checking it at x=5, we obtain:

y = 25*5 + 35 = 125 + 35 = 160.

That checks.

Now to figure an 8-hr job, set x=8 and use the equation"

y = 25*8 + 35.

y = 200 + 35.

y = 235.

That means an 8-hr job costs $235.

3 0
3 years ago
Combine like terms 9-5=9x-6x
4vir4ik [10]

Answer:

4 = 3x

Step-by-step explanation:

9-5=9x-6x

Combine like terms

4 = 3x

We can solve for x

Divide by 3

4/3 = 3x/3

4/3 =x

7 0
3 years ago
Find the missing angle measures<br> m∠3<br> m∠4<br> m∠5<br> m∠6<br> Please show work
Alla [95]

Answer:

75

Step-by-step explanation:

x+45+60=180

x+105=180

x=180-105

x=75

7 0
3 years ago
DIRECTIONS: Use this information to answer Parts A, B, and C.
Talja [164]

Answer:

V=706.85

Step-by-step explanation:

Well, first of when you want to find the volume of the cone you need to have a radius and hieght. And the radius is half the diameter, so divide the diameter into half: 10/2=5 in. and you already have the height so just plug in the numbers.

Formula: V= \frac{1}{3}\pir^{2}h ---> V= \frac{1}{3}\pi(5^{2})(27)

And put the plugged in formula in your calculator and you'll find the answer!

V=706.85

I hope this helped.

3 0
3 years ago
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