Question

A cloth manufacturing company claims that the mean tearing strength of their curtain fabric is 120 pounds. A government inspection agency conducted tests on 49 curtain lengths revealing a mean strength of 115 pounds with a standard deviation of 20 pounds. At the 10% level of significance, does the governments’ information show that the mean tearing strength of the fabric is lower than manufacturer’s claim?

Answer 1

Solution :

The null and alternative hypothesis is ,

H0 :   = 120

Ha : < 120

Test statistic (t) =

= ( - ) / s / n

= (115 - 120) / 20 / 49

Test statistic = -1.75

P-value = 0.0433

= 0.10

P-value <

Reject the null hypothesis .

There is sufficient evidence to conclude that the mean tearing strength of the fabric is lower than manufacturer’s claim