Question

1.

A random sample of ten households in College Park revealed they generated a mean of 10.91 pounds of garbage per week with a standard deviation of 4.736 pounds. Construct the 80% confidence interval to estimate the mean amount of garbage all College Park households generate per week

8.1646 pounds to 13.6554 pounds

7.5220 pounds to 14.2980 pounds

8.8387 pounds to 12.9813 pounds

6.0429 pounds to 15.7771 pounds

2.

Suppose National Collegiate Athletic Association [NCAA] rules state all student-athletes are to receive an average of 50 hours of academic support, per term. A random sample of 49 University of Maryland student-athletes revealed a mean of 47.5 hours of academic support per term. If the calculated value for the associated test statistic equaled -1.75, what was the standard deviation of the number of hours of academic support the student-athletes in the sample received per term?

12

15

7

10

Answer 1

Solution:

Question 1)

Given:

Sample size = n = 10

Sample mean =

Sample Standard Deviation = s = 4.736

Confidence level = c = 80%

Formula:

where

t_c is t critical value for c = 80%  confidence level

Thus two tail area = 1 - c = 1 - 0.80= 0.20

df = n - 1 =  10- 1 = 9
Look in  t table for df =9 and two tail area = 0.20 and find t critical value

t_c = 1.383

thus

thus

Question 2)

Given:

Mean =

Sample size = n = 49

Sample mean =

test statistic value = z = -1.75

find standard deviation