A random sample of 250 students at a university finds that these students take a mean of 15.8 credit hours per quarter with a standard deviation of 2.3 credit hours. Estimate the mean credit
Hours taken by a student each quarter using a 90% confidence interval. Round to the nearest
Thousandth.
A) $15.8 \pm .010$
B) $15.8 \pm .158$
C) $15.8 \pm .239$
D) $15.8 \pm .015$

Question

A random sample of 250 students at a university finds that these students take a mean of 15.8 credit hours per quarter with a standard deviation of 2.3 credit hours. Estimate the mean credit
Hours taken by a student each quarter using a 90% confidence interval. Round to the nearest
Thousandth. 
A) $15.8 \pm .010$
B) $15.8 \pm .158$
C) $15.8 \pm .239$
D) $15.8 \pm .015$

Quizplus · Accepted Answer

The 90% confidence interval is calculated using the formula: mean ± (z * (standard deviation/√n)). For a 90% confidence level, z is approximately 1.645. Thus, the margin of error is 1.645 * (2.3/√250) ≈ 0.239.

A Random Sample of 250 Students at a University Finds 15.8±.01015.8 \pm .01015.8±.010

A Random Sample of 250 Students at a University Finds $15.8 \pm .010$