Question

A process for making compression springs is under control if the free lengths of the springs have a mean of 2.5 cm. What can we say about this process if a sample of 10 of these springs has a mean of 2.53 cm and a standard deviation of 0.02 cm?

Answer 1

Solution :

This is the two tailed test .

The null and alternative hypothesis is ,

H₀ :   = 2.5

H_a : 2.5

Test statistic = t

= ( - ) / s / n

= (2.53 - 2.5) / 0.02 / 10

Test statistic = 4.74

df = 9

P-value = 0.0011

= 0.05

P-value <

Reject the null hypothesis .

There is sufficient evidence to support this process .