Question

For a standard normal curve, find the z-score that separates the bottom 90% from the top 10%.

Answer 1

You're looking for
`k` such that


`\mathbb P(Z<k)=0.90`

A z-score table or any calculator with an inverse CDF functionality gives an answer of about


`k\approx1.2816`

For example, on a TI-83 calculator, you would use

invNorm(.90)

or

invNorm(.90, 0, 1)