Question

For a population with u=100 and a=20, what is the z-score that corresponds to x=90?

Answer 1

I guess that u = μ & that a=σ. If so:

μ =100 & that σ =20 & x=20

Z score = (x-μ) / σ  ==> Z score = (90-100)/20 ==> Z = - 0.5