Question

A lumber company is making boards that are 2578.0 millimeters tall. If the boards are too long they must be trimmed, and if the boards are too short they cannot be used. A sample of 20 is made, and it is found that they have a mean of 2580.2 millimeters with a variance of 64.00. A level of significance of 0.1 will be used to determine if the boards are either too long or too short. Assume the population distribution is approximately normal. Find the value of the test statistic. Round your answer to three decimal places.

Answer 1

Solution :

= 2578

= 2580.2

² = 64

= 8

n = 20

Test statistic = z

= ( - ) / / n

= (2578 - 2580.2) / 8 / 20

= -1.230

Test statistic = -1.230