Question

Scores on the SAT verbal test in recent years follow approximately the N(504,111) distribution.

The proportion of students scoring under 400 is?

Answer 1

If you know how to use built-in statistical functions on a calculator such as the TI-83 or 84, you can solve this problem with one press of the ENTER key on the calculator:

normalcdf(-100, 400, 504, 111) = 0.17 (answer)

Otherwise, find the z-score associated with 400:

400-504
z= ------------- , and the use a z-score table to find the area under the
111 standard normal curve to the left of this z value.