Question

15. Ellen records the time it takes for her to commute to work on 100 consecutive mornings and finds that the times are approximately Normally distributed with a mean of 25 minutes and a standard deviation of 4.6 minutes. What percentage of the time does Ellen’s commute take less than 14 minutes?
(a) 0.8%
(b) 1.1%
(c) 1.6%
(d) 98.3%
(e) 99.2%
16. Ellen records the time it takes for her to commute to work on 100 consecutive mornings and finds that the times are approximately Normally distributed with a mean of 25 minutes and a standard deviation of 4.6 minutes. What percentage of the time does Ellen’s commute take between 14 and 36 minutes?
(a) 0.8%
(b) 1.1%
(c) 1.6%
(d) 98.3%
(e) 99.2%
17. Ellen records the time it takes for her to commute to work on 100 consecutive mornings and finds that the times are approximately Normally distributed with a mean of 25 minutes and a standard deviation of 4.6 minutes. What is the 80th percentile for Ellen’s driving times?
(a) -0.84
(b) 0.84
(c) 3.9
(d) 25.8
(e) 28.9
18. Ellen records the time it takes for her to commute to work on 100 consecutive mornings and finds that the times are approximately Normally distributed with a mean of 25 minutes and a standard deviation of 4.6 minutes. On Tuesday, it takes 19 minutes to get to work. What is the z-score for her commute that day?
(a) -6.0
(b) -1.30
(c) -0.77
(d) 0.77
(e) 1.30

Answer 1

First one A second one C third one d 4th one E