posted by Celest .
A set of 50 data values has a mean of 30 and a variance of 4.
I. Find the standard score (z) for a data value = 26.
II. Find the probability of a data value < 26.
I think the first part is z=(26-30)/4 = -4/4 = -1. I am not sure how to go about the second problem. I could use any help. Thanks
1. Z =( score-mean)/SD
Variance = SD squared
2. Same equation, but find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to Z.