Three percent of a man's body is essential fat; for a woman the percentage is closer to 12.5%. As the name implies, essential fatis necessary for a normal healthy body. Fat is stored in small amounts throughout the body. Too much fat, however, can be dangerous to your health. For men between 18 and 39 years old, a healthy percent of body fat ranges from 8% to 19%; for women of the same age, it's 21% to 32%. Measuring body fat can be tedious and expensive. The "standard reference" measurement is by dual-eneregy absorptiometry (DEXA), which involves two low-dose X-ray generators and takes from 10 to 20 minutes. Because of the time and expense involved with the DEXA method, health professionals would like to be able to make a useable prediction of body fat from easily measurable variables such as weight or waist size. This Excelfile shows the waist size (inches), weight (pounds) and percent body fat for 20 individuals. 

Question 1. What is the slope of the least squares regression line of %body fat on waist size? Correct: Your answer is correct. (use 4 decimal places). 

Question 2. Findsb1, the estimate of the standard deviation ?b1 of the least squares slope b1 (use 4 decimal places). Correct: Your answer is correct. sb1, estimate of 

 Question 3. Determine the 90% confidence interval for the slope of the least squares regression line of %body fat on waist size. Correct: Your answer is correct. lower bound Correct: Your answer is correct. upper bound

Question4. Determine a 90% confidence interval for the mean %body fat found in people with 40-inch waists (use 2 decimal places). lower bound upper bound 

Question 5. Determine a 90% prediction interval for the body fat of an individual with a 40-inch waist (use 2 decimal places). lower bound upper bound

Waist (in.)	Weight (lb)	Body Fat (%)
32	175	6
36	181	21
38	200	15
33	159	6
39	196	22
40	192	31
41	205	32
35	173	21
38	187	25
38	188	30
33	188	10
40	240	20
36	175	22
32	168	9
44	246	38
33	160	10
41	215	27
34	159	12
34	146	10
44	219	28