How many weeks of data must be randomly sampled to estimate the mean weekly sales of a new line of athletic footwear? We want 98% confidence that the sample mean is within $400 of the population mean, and the population standard deviation is known to be $1400.

So the answer for this case would be n=67 rounded up

Step-by-step explanation:

Information given

represent the sample mean for the sample  

population mean

represent the sample standard deviation

n represent the sample size  

Solution to the problem

The margin of error is given by this formula:

   (a)

And on this case we have that ME =400 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

  (b)

The critical value for 98% of confidence interval now can be founded using the normal distribution. And the critical value would be , replacing into formula (b) we got:

So the answer for this case would be n=67 rounded up

step-by-step explanation:

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-22

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