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Chapter 8: Q.8.4 (page 453)

Refer back to the pizza-delivery Try It exercise. The population standard deviation is six minutes and the sample mean delivery time is 36minutes. Use a sample size of 20. Find a95% confidence interval estimate for the true mean pizza delivery time

Short Answer

Expert verified

The interval estimate for the true mean pizza delivery time is (33.37,38.63)

Step by step solution

01

Given Information

Given the data that,

standard deviation is six minutes s and the sample mean delivery time is 36 minutes. Use a sample size of 20.

02

Explanation

The sample mean is36minutes, that is,x¯=36

The random sample of20pizza delivery restaurants, that is,n=20

The standard deviation is6, that is,σ=6

03

Explanation

Now, using the procedures below, compute the confidence interval using a Ti-83 calculator.

Press STAT and use the arrow (?) to TESTS

Now press the arrow (↓)to 7: Zinterval and press enter

Then use the arrow (→)to STATS and press enter

Now press the arrow (?) and enter the inputs as shown below

Now press the arrow (?) to the calculator and press enter. The output is given below,

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Most popular questions from this chapter

Construct a 95% confidence interval for the population mean weight of the heads of lettuce. State the confidence interval, sketch the graph and calculate the error bound.

A sample of 20heads of lettuce was selected. Assume that the population distribution of head weight is normal. The weight of each head of lettuce was then recorded. The mean weight was 2.2pounds with a standard deviation of 0.1pounds. The population standard deviation is known to be 0.2pounds.

What would happen if 40 heads of lettuce were sampled instead of 20, and the confidence level remained the same?

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Construct a 90% confidence interval, and state the confidence interval and the error bound.

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In words, define the random variable X.

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