Question

A machine produces metal rods used in an automobile suspension system. A random sample of 15 rods is selected, and the diameter is measured. The resulting data (in millimeters) are as follows: 8.24, 8.25, 8.20, 8.23, 8.24, 8.21, 8.26, 8.26, 8.20, 8.25, 8.23, 8.23, 8.19, 8.22, 8.24. A conclusion has to be made at 1% significance that the mean rod diameter is greater than 8.20. What is the value of t_calc? Please report your answer in 3 decimal places.

Answer 1

Solution :

Given that,

This is the right tailed test .

= 8.23

s = 0.02

sample size = n = 15

Degrees of freedom = df = n - 1 = 15 - 1 = 14

Test statistic = t

= ( - ) / / n

= (8.23 - 8.20) / 0.02 / 15

= 5.281

Test statistic = 5.281

tcal = 5.281