cook-it rice cooker has a mean time before failure of 38 months with a standard deviation of 4 months, and the failure times are normally distributed. what should be the warranty period, in months, so that the manufacturer will not have more than 7% of the rice cookers returned? round your answer down to the nearest whole number.

A p-value calculates the likelihood of getting the outcomes that were observed, presuming that the null hypothesis is correct. The statistical significance of the difference that was found increases with decreasing p-value. Statistical significance is commonly defined as a p-value of 0.05 or less. The sample data, test type, and sampling distribution of the test statistic under the null hypothesis are used to determine the p-value (lower-tailed test, upper-tailed test, or two-sided test).

Given,

Cook-it rice cooker has a mean time before failure of 38 months with a standard deviation of 4 months, and the failure times are normally distributed.

The 7th percentile, or X when Z has a p-value of 0.08, or X when Z = 0.4720, should serve as the warranty period.

Z = X - Mean/ standard deviation

0.472 = x - 38/4

0.472 (4) - x - 38

1.888 = x - 38

x = 39.88

x = 40

In 40 months, so that the manufacturer will not have more than 7% of the rice cookers returned.

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