Have American males (AMs) gotten heavier over the last 20 years? A ran

Isaiah Alsup

Isaiah Alsup

Answered question

2021-12-04

Have American males (AMs) gotten heavier over the last 20 years? A random sample 77 AMs in 2019 had a mean weight of x=189.030 pounds. A random sample 93 AMs in 1999 had a mean weight of y=184.795 pounds. It is recognized that the true standard deviation of 2019 AMs weights is
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 normally distributed. In summary:
TypeSample SizeSample MeanStandard Deviation2019 Data(X)77189.03014.041999 Data(Y)93184.79510.03
i) If we used this data to test H0:μxμy=0 against the alternative
Ha:μxμy>0 then what would the p value have been?
j)If we used this data to test H0:μxμy=0 against the alternative
Ha:μxμy0 then what would the p value have been?

Answer & Explanation

Sculd1987

Sculd1987

Beginner2021-12-05Added 19 answers

Step 1
i) Null hypothesis:
H0:μxμy=0
Alternative hypothesis:
Ha:μxμy>0
The test statistic is as follows:
Z=x1x2σ12n1+σ22n2
=189.030184.795(14.04)277+(10.03)293
=2.2192
Step 2
Thus, the test statistic value is 2.2192.
Computation of P-value:
The P-value can be obtained using the excel formula “= (1-NORM.S.DIS (2.2192,1)”.
The p-value is 0.01323.
Step 3
j) Null hypothesis:
H0:μxμy=0
Alternative hypothesis:
Ha:μxμy0
Thus, the test statistic value is 2.2192.
Computation of P-value:
The P-value can be obtained using the excel formula “=2×(1NORM.S.DIS(2.2192,1)”.
The p-value is 0.02647.

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