The mean weight of loads of rock is 46.0 tons with a standard deviation of 10.0 tons. If 9 loads are chosen at random for a weight check, find the probability that the mean weight of those loads is less than 42.00
Tons. Assume that the variable is normally distributed.
A) 0.1151
B) 0.3151
C) 0.1551
D) 0.4008

Question

Quizplus · Accepted Answer

The standard error of the mean is 10/√9 = 3.33. The z-score for a sample mean of 42 is (42-46)/3.33 = -1.20. Using the standard normal distribution table, the probability of a z-score being less than -1.20 is approximately 0.1151.

The Mean Weight of Loads of Rock Is 46