Question

The entity X ~ N(0, 1) (Standard normal distribution). (a) Find q such that Pr(X <= q) = 0.25 (the first quartile of the standard normal distribution); (b) Find q such that Pr(X <= q) = 0.75 (third quartile of the standard normal distribution)

Answer 1

The first quartile is at -0.67 and the third quartile is at 0.67. U can refer standard normal table for the answer.

For more precise answer one can use percentile calculator of normal distribution.

Using calculator, the first quartile is at -0.6745 and third quartile is at 0.6745.