SOLUTION: A medical doctor who wanted to study the heights of adult men and women took a random sample of 150 adult men and 120 adult women and found the following summary results. Mean He

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Question 1183990: A medical doctor who wanted to study the heights of adult men and women took a random
sample of 150 adult men and 120 adult women and found the following summary results.
Mean Height of Adult Men was 170cm and Standard Deviation of Adult Men was 8cm;
Mean Height of Adult Women was 164cm and Standard Deviation of Adult Women was 6cm.
Find a 90% confidence interval for the difference of mean height of adult men and
women.
Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
90%CI half-interval with n=270 is essentially z(0.95)*sqrt((s1^2/n1)+(s2^2/n2))
=1.645*sqrt ((64/150)+(36/120))
=1.645*0.8524
=1.40
the difference in heights is 6 cm
so 90% CI for (men-women)=(4.6, 7.4) cm
Using t where the value is 1.647 (df=268), the answer is the same to one decimal place.