Statistics: Confidence Intervals and T-Interval for the Mean

A 2007 study reported in Science magazine stated that fifth-grade teachers scored a meanof 3.4 (out of 7) points for “providing evaluative feedback to students on their work.” Assume that the sample size was 36 and the sample standard deviationwas 1.5.

a. Find T(alpha/2) for a confidence intervalwith 90% confidence.
b. Compute and interpret the margin of error E for a confidence interval with 90% confidence.
c. Construct and interpret a 90% confidence interval for the population mean points scored by fifth-grade teachers for providing evaluative feedback.

The solution determines the confidence intervals and the t-interval mean.