You want to estimate the mean weight loss of people one year after using a popular weight-loss program being advertised on TV. How many people on that program must be surveyed if we want to be 95% confident that the sample mean weight loss is within 0.25 lb of the true population mean? Assume that the population standard deviation is known to be 10.6 lb.

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Answer:

6907 people on that program must be surveyed if we want mean weight loss as 0.25 lb and standard deviation as 10.6 lb.

Step-by-step explanation:

Given that mean of weight loss in 0.25 lb and standard deviation is 10.6 lb.

For 95% confident level z-score must be 1.96.

That is [tex]Z_{c}[/tex]=1.96

Now required sample size is [tex](\frac{Z_{c} X(SE)}{m})^{2}[/tex]

Where SE means standard deviation=10.6 lb and mean m=0.25 lb

Hence sample size=[tex](\frac{1.96X10.6}{0.25})^{2}=6906.27[/tex]

Which we always should round up that is 6907.