4. For a normal distribution, find the z-score that separates the distribution as follows: a) Separate the highest 30% from the rest of the distribution.
b) Separate the lowest 40% from the rest of the distribution.
c) Separate the highest 75% from the rest of the distribution.

Let denote the cumulative distribution function for the standard normal distribution (mean 0, standard deviation 1). Then you're looking for z such that

(a)

(b)

(c)

To get the corresponding z-score for each of 0.70, 0.40, and 0.25, take the inverse CDF of both sides:

(a)

(b)

(c)

lol

step-by-step explanation: