Question

A manufacturer has developed a new fishing line, which the company claims has a mean breaking strength of 14 kilograms with a standard deviation of 1.7 kilograms. Believing the mean breaking strength is less than what company has claimed, a customer protection agency took a random sample of 20 such fishing lines and found that the mean breaking strength for this sample is 14.5 kilograms. Given the breaking strength of all such lines have a normal distribution, test whether the agency’s suspicion is valid or not at 3% significance level.

Answer 1

given data are:-

sample mean () = 14.5

sample size (n) = 20

population sd () = 1.7

hypothesis:-

[ claim ]

test statistic be:-

the p value is :-

[ in any blank cell of excel type =NORMSDIST(1.3153)]

decision:-

p value =0.9058 > 0.03 (alpha)

we fail to reject the null hypothesis and conclude that there is not enough evidence to claim the agency’s suspicion to be valid.

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