Question

Assume that a sample is used to estimate a population mean μμ. Find the 80% confidence interval for a sample of size 749 with a mean of 51.5 and a standard deviation of 14.8.

Enter your answers accurate to one decimal place:

_ < μ < _

Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.

Answer 1

Standard error of mean = s / = 14.8 / = 0.5407802

For larger sample size, we can use z value to compute the confidence interval.

Critical z value for 80% confidence interval is 1.282

80% confidence interval for mean is,

51.5 - 1.282 * 0.5407802 < <  51.5 + 1.282 * 0.5407802

50.80672 < <  52.19328