A Researcher Is Interested in Whether Students Who Attend Private $\sigma$

Short Answer

A researcher is interested in whether students who attend private elementary schools do better or worse on a standard test of intelligence than the general population of elementary school children. A random sample of 75 students at a private elementary school is tested and has a mean intelligence test score of 103.5. The average for the general population of elementary school children is 100 ( $\sigma$ = 15).
-Compute Z_obt.