Question

In: Statistics and Probability

A medical researcher wants to investigate the amount of time it takes for patients' headache pain...

A medical researcher wants to investigate the amount of time it takes for patients' headache pain to be relieved after taking a new prescription painkiller. She plans to use statistical methods to estimate the mean of the population of relief times. She believes that the population is normally distributed with a standard deviation of 15 minutes. How large a sample should she take to estimate the mean time to within 4 minutes with 95% confidence?

Solutions

Expert Solution

We have given here,                  
                  
Population standard deviation =15 minutes  
Margin of error =E=4 minutes  
Level of significance =   1-0.95=0.05  
Z critical value is (by using Z table)=   1.96  
Sample size formula is                   


=54.02      

n=55 Approximately

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