Question

The mean breaking strength of yarn used in manufacturing drapery material is required to be at least 100 psi. Past experience has indicated that the standard deviation of breaking strength is 2.3 psi. A random sample of 9 specimens is tested, and the average breaking strength is found to be 100.6 psi.Calculate the P-value

Answer 1

The P-value is 0.2177.

Explanation:

Test statistic (z) = (sample mean - population mean) ÷ (sd/√n)

sample mean = 100.6 psi

population mean = 100 psi

population sd = 2.3 psi

n is sample size = 9

z = (100.6 - 100) ÷ (2.3/√9) = 0.6 ÷ 0.767 = 0.78

From the standard normal distribution table, the cumulative area of the test statistic is obtained by taking the value of 0.7 under 0.08. The cumulative area is 0.7823.

P-value = 1 - 0.7823 = 0.2177