Question

A highway inspector needs an estimate of the mean weight of trucks crossing a bridge on the interstate highway system. she selects a random sample of 49 trucks and finds a mean of 15.8 tons with a sample standard deviation of 3.85 tons. the 90 percent confidence interval for the population mean is:

Answer 1

Answer:

14.90 to 16.70 tons

Step-by-step explanation:

We are given;

Sample size; n = 49

Mean; x¯ = 15.8

Sample standard deviation; s = 3.85

At 90% Confidence interval, z = 1.645

Formula for confidence interval is;

CI = x¯ ± z(s/√n)

Thus;

CI = 15.8 ± 1.645(3.85/√49)

CI = 15.8 ± 0.90

CI = 14.90 to 16.70 tons