There was an old woman who lived in a shoe. She had so many children she didn’t
ID: 3154627 • Letter: T
Question
There was an old woman who lived in a shoe. She had so many children she didn’t know what to do, so she measured their heights. First, she measured the heights of 13 girls and found the average height was 31.4 inches. Next she measured the height of 7 boys and found their height to be an average of 38.1 inches. From the U.S. Statistical Abstract, she found that the variance in girls’ heights in 100in2 and in boys 80in2. Help the old lady find a 95% confidence interval for the difference in height between her boys and girls. You may assume that height follows a normal distribution.
Explanation / Answer
Std Dev.2: 8.94
M1-M2=31.4-38.1=-6.7
sd=16.18; se=4.3715
95% CI of difference:
-15.268 <-6.7< 1.868 (Wald)
t-difference: -1.533
df-t: 13.2; p= 0.0718
(left p: 0.9282; two sided: 0.1436)
Difference not significant at 5%
Mean 1: 31.4 Mean 2: 38.1 N1: 13 N2: 7 Std Dev.1: 10Std Dev.2: 8.94
M1-M2=31.4-38.1=-6.7
sd=16.18; se=4.3715
95% CI of difference:
-15.268 <-6.7< 1.868 (Wald)
t-difference: -1.533
df-t: 13.2; p= 0.0718
(left p: 0.9282; two sided: 0.1436)
Difference not significant at 5%
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