#7 An IQ test was given to a simple random sample of 85 students
at a certain college. The sample mean score was 110.2. Scores on
this test are known to have a standard deviation of σ = 20. It is
desired to construct a 90% confidence interval for the mean IQ
score of students at this college.
a. what is the point estimate?
b. find the critical value.
c. find the standard error.
d. find the margin of error.
e. construct the 90% confidence interval.
f. is it likely that the population mean μ is greater than 100?
explain.
9. Find the critical value tα/2 needed to construct a confidence
interval of the given level with the given sample size
a. level 95%, sample size 23
b. level 90%, sample size 57