Question

1. Give and interpret the 95% confidence intervals for males and females on the HEIGHT variable. Which is wider and why?
2. Give and interpret the 99% confidence intervals for males and females on the HEIGHT variable. Which is wider and why?
3. Find the mean and standard deviation of the DRIVE variable and then determine the percentage of data points from that data set that we would expect to be less than 40.

   Height (inches)	Sleep (hours)	Gender
   61	7	M
   62	7	F
   63	5	F
   63	7	F
   64	6	F
   65	8	F
   65	7	F
   66	8	F
   66	5	M
   67	8	M
   67	8	F
   67	4	F
   67	8	F
   68	8	M
   68	6	M
   69	8	M
   69	8	M
   69	8	M
   69	7	F
   69	10	M
   69	6	F
   69	7	M
   70	8	F
   70	5	F
   70	8	F
   70	7	F
   70	7	M
   71	4	M
   71	9	M
   71	8	M
   73	7	F
   73	7	M
   74	8	M
   74	8	M
   75	10	M

Answer 1

MINITAB used

· Give and interpret the 95% confidence intervals for males and females on the HEIGHT variable. Which is wider and why?

Descriptive Statistics

Sample	N	Mean	StDev	SE Mean	95% CI for μ
Male Height	18	69.667	3.308	0.780	(68.022, 71.312)
Female Height	17	67.059	3.112	0.755	(65.459, 68.659)

μ: mean of Male Height, Female Height

confidence interval for male height is wider because its standard error is large.

· Give and interpret the 99% confidence intervals for males and females on the HEIGHT variable. Which is wider and why?

Descriptive Statistics

Sample	N	Mean	StDev	SE Mean	99% CI for μ
Male Height	18	69.667	3.308	0.780	(67.407, 71.926)
Female Height	17	67.059	3.112	0.755	(64.854, 69.263)

μ: mean of Male Height, Female Height

confidence interval for male height is wider because its standard error is large.