According to a study of 90 truckers, a trucker drives, on average, 540 miles per
ID: 3320981 • Letter: A
Question
According to a study of 90 truckers, a trucker drives, on average, 540 miles per day. If the standard deviation of the miles driven per day for the population of truckers is 40, find the 99% confidence interval of the mean number of miles driven per day by all truckers. (answer rounded to the nearest whole number)
Question 7 options:
The confidence interval for the mean is between 500 and 556
The confidence interval for the mean is between 529 and 551
The confidence interval for the mean is between 520 and 530
none
The confidence interval for the mean is between 500 and 556
The confidence interval for the mean is between 529 and 551
The confidence interval for the mean is between 520 and 530
none
Explanation / Answer
Z for 99% confidence interval = Z0.005 = 2.58
Confidence interval = (mean + Z0.005 * sd/sqrt(n))
= (540 + 2.58 * 40 / sqrt(90))
= (540 + 11)
= (529, 551)
Option-B)