The Standard Normal Distribution

Question

For a standard normal distribution, given:

P(z < c) = 0.4027

Find c.

Answer 1

Hi Marcella,

This question in not that bad once you understand what you are doing.

You have P(z≤c) = 0.4027.

Our standard normal table tells us the Pr(Z≤z) so we find the z value in the standard normal table that gives a value of approximately 0.4027.

This is φ^-1(0.4027) = z

This value is z = -0.246.

So basically if you have the percentage that z is less than and you want to find the z value you look up the percentage in the standard normal table and find the z value that corresponds to it. Hope this is helpful.