Find the Z scores that separate the middle 80% of the distribution from the area in the tales of the standard normal distribution

Question

it doesn’t provide a mean or standard deviation

Answer 1

The z distribution has a mean of 0 and a standard deviation of 1. You want to find the z value in the table that has as area to the left of .90 and the value that has an area of .10. These are the bounds for your z values that separate 80% in the middle from 10% in each tale.