You work for a consumer advocate agency and want to find the mean repair cost of a washing machine. as part of your study, you randomly select 40 repair costs and find the mean to be $100.00. from past studies, you assume that the standard deviation σ is $17.50.

construct a 90% confidence interval and interpret it.

construct a 95% confidence interval and interpret it.

construct a 99% confidence interval and interpret it.

determine the minimum required sample size if you want to be 95% confident that the sample mean is within $10 of the population mean.

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Ответ:

prettykevahk

30.05.2021

Mathematics

The factored form a^2-121 is (a+11)(a-11) .

Step-by-step explanation:

Given : a^2-121

We have to write the given expression in factored form.

Factor form of an expression is writing the expression in lower power form such that the product of factors given the original expression

Consider the given expression a^2-121 .

We know the algebraic identity x^2-y^2=(x+y)(x-y)

Here a^2-121=a^2-(11)^2 .

Comparing with identity stated above , we have x= a , b = 11 , thus, we get

a^2-(11)^2=(a+11)(a-11) .

Thus, the factored form a^2-121 is (a+11)(a-11) .

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