QUESTION 18When engaging in weight-control (fitness/fat burning) types of exercise, a person is expected to attainapproximately 60% of his or her maximum heart rate. For 20-year-olds, this rate is approximately 120bpm. A simple random sample of thirty 20-year-olds was taken, and the sample mean was found to be107 bpm, with a standard deviation of 45 bpm. Researchers wonder if this is evidence to concludethat the expected level is actually lower than 120 bpm.What are the degrees of freedom?9910029O 49

Answered: When engaging in weight-control…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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Steve believes that his wife's cell phone battery does not last as long as his cell phone battery. On eleven different occasions, he measured the length of time his cell phone battery lasted and calculated that the mean was 16.4 hours with a standard deviation of 6.4 hours. He measured the length of time his wife's cell phone battery lasted on seven different occasions and calculated a mean of 23.3 hours with a standard deviation of 4.2 hours. Assume that the population variances are the same. Let Population 1 be the battery life of Steve's cell phone and Population 2 be the battery life of his wife's cell phone. Step 1 of 2: Construct a 90 % confidence interval for the true difference in mean battery life between Steve's cell phone and his wife's. Round the endpoints of the interval to one decimal place, if necessary.
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Steve believes that his wife's cell phone battery does not last as long as his cell phone battery. On eight different occasions, he measured the length of time his cell phone battery lasted and calculated that the mean was 19.7 hours with a standard deviation of 9.4 hours. He measured the length of time his wife's cell phone battery lasted on twelve different occasions and calculated a mean of 18.9 hours with a standard deviation of 5.3 hours. Assume that the population variances are the same. Let Population 1 be the battery life of Steve's cell phone and Population 2 be the battery life of his wife's cell phone. Step 1 of 2: Construct a 90 % confidence interval for the true difference in mean battery life between Steve's cell phone and his wife's. Round the endpoints of the interval to one decimal place, if necessary.

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