Q13 Ages of students A simple random sample of 145 US colleg

Q13

Ages of students: A simple random sample of 145 U.S. college students had a mean age of 21.37 years. Assume the population standard deviation is sigma = 4.42 years. Construct a 98% confidence interval for the mean age of U.S. college students. Round the answers to two decimal places. A 98% confidence interval for the mean age of U.S. college students is [ ]

Solution

confidence interval:

mean +/- z*sd/square root of n

The Z to use for a 98% confidence is 2.33

21.37 +/- 2.33*4.42/square root of 145

21.37 +/- 0.86

lower limit: 21.37 - .86 = 20.51

Upper limit: 21.37 + .86 = 22.23

98% confidence interval: (20.51, 22.23)