Scores on a test are Normally distributed with mean 78 and standard deviation 8. Find the probability that a randomly chosen student scored between 70 and 80 on the test.

Question

Scores on a test are Normally distributed with mean 78 and standard deviation 8.  Find the probability that a randomly chosen student scored between 70 and 80 on the test.

oobleck · Answer

70 = µ - 1σ 80 = µ + 0.125σ so, what does your Z table tell you? You can play around with Z-table stuff at https://davidmlane.com/hyperstat/z_table.html