Areport in a research journal states that the average weight loss of people on a certain drug is 27 lbs with a standard deviation of 5 lbs. if this study is repeated, how large should the sample size be so that the margin of error would be no more than 2.5 lbs with 95% confidence?

 16

Step-by-step explanation:

We know that the formula to find the sample size is given by :-

, where = population standard deviation.

E = Margin of error

= Two-tailed z-value for significance level of

As per given , we have

Using z-value , table

Margin of error = 2.5 lbs

Then, the required sample size would be :_

Hence, the required sample size = 16

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