3. Find the sample size required to estimate the mean IQ of professional musicia

Question

3.

Find the sample size required to estimate the mean IQ of professional musicians, assuming that we want 95% confidence that the mean from the sample is within 3 IQ points of the true mean and that the true standard deviation in IQ is 15.

4.

The US Department of Health and Human Services reports that the mean length of stay in hospital for 35 sickle cell anemia patients was 5.3 days, with a sample standard deviation of 7.6 days. What is the critical value required to estimate a 90% confidence interval of the mean.

Explanation / Answer

Ans:

3)z value for 95% CI is 1.96

sample size,n=1.962*152/32

n =96

4)sample size,n=35

n>=30,so we can use z distribution.

critical z value for 90% CI is 1.645

If we use t distribution,then

df=35-1=34

critical t value=TINV(0.1,34)=1.691

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