Question

(Also how to solve on ti-84)

1.

Fuel efficiency. Computers in some vehicles calculate various quantities related to performance. One of these is the fuel efficiency, or gas mileage, usually expressed as miles per gallon (mpg). One of the authors of this book conducted an experiment with his 2006 Toyota Highlander Hybrid by randomly recording mpg readings shown on the vehicle computer while the car was set to 60 miles per hour by cruise control. Here are the mpg values from the experiment:

37.2	21	17.4	24.9	27
19	26.1	25.8	41.4	34.4
36.9	38.8	35.3	32.3	23.9
32.5	25.3	26.5	28.2	22.1

Sigma, σ, is unknown.

What is the standard error of the mean? (use 3 decimal places)

What is the 98% confidence interval for the mean mpg? [ mpg, mpg] (use 2 decimal places)

Answer Key: 1.541, 24.89, 32.71

Feedback: Incorrect 2. Clothing for runners. Your company sells exercise clothing and equipment on the Internet. To design the clothing, you collect data on the physical characteristics of your different types of customers. Here are the weights (in kilograms) for a sample of 24 male runners. Assume that these runners can be viewed as a random sample of your potential male customers. 68.7 61.8 63.2 53.1 62.3 59.7 65.6 65.5 56 57.8 66 62.9 55.4 58.9 60.9 69.2 63.7 67.8 53.6 65 55.8 60.4 69.3 62.1 Give a 99% confidence interval for μ, the mean of the population from which the sample is drawn. What is the sample standard deviation? kg What is the T confidence coefficient value corresponding to a 99%? (use 3 decimal places) What is the margin of error? (use 3 decimal places) What is the 99% confidence interval? [ kg, kg] Answer Key: 4.8579, 2.807, 2.783, 59.01, 64.65

Answer 1

1. Given : Sample size=n=20

Sample mean=

Sample standard deviation = s =

Significance level=

The standard error =S.E.=

The 98% confidence interval for the mean is ,

2. Given : Sample size=n=24

Sample mean=

Sample standard deviation = s =

Significance level=

The standard error =S.E.=

The T confidence coefficient value corresponding to a 99% =

The margin of error is , M.E. =

The 99% confidence interval for the mean is ,