The mean weight of trucks traveling on a particular section of I-475 is not known. A provincial highway inspector needs an estimate of the mean. He selects a random sample of 49 trucks passing the weighing station and finds the mean is 15.8 tonnes, with a standard deviation of the sample of 4.2 tonnes. What is probability that a truck will weigh less than 14.3 tonnes?
A) 0.0062
B) 0.3632
C) 0.1368
D) 0.4938
E) None of the choices are correct

Question

Quizplus · Accepted Answer

The probability that a truck will weigh less than 14.3 tonnes is 0.0062. This is because the z-score for a truck weighing 14.3 tonnes is (14.3 - 15.8) / 4.2 = -0.357, and the area under the normal distribution curve to the left of -0.357 is 0.0062.

The Mean Weight of Trucks Traveling on a Particular Section