A First Course in Probability (10th Edition)
10th Edition
ISBN: 9780134753119
Author: Sheldon Ross
Publisher: PEARSON
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Have American males (AMs) gotten heavier over the last 20 years? A random sample 77 AMs in 2019 had a
σx
= 14.04 pounds while it is recognized that the true standard deviation of 1999 AMs weights is
σy
= 10.03 pounds. The true (unknown) mean of 2019 AMs weights is
μx
pounds, while the true (unknown) mean of 1999 AMs weights is
μy
pounds. Weights are known to be a
| Type | Sample Mean | Standard Deviation | |
|---|---|---|---|
| 2019 Data (X) | 77 | 189.030 | 14.04 |
| 1999 Data (Y) | 93 | 184.795 | 10.03 |
a)Calculate the variance of the random variable X which is the mean of the weights of the 77 AMs from 2019.
b)Calculate the variance of the random variable Y, which is the mean of the weights of the 93 AMs from 1999.
c) Calculate the variance of X - Y?
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