posted by jau .
For a normal distribution with µ = 200 and ó = 50, what X values form the boundaries for the middle 60% of the distribution?
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (± .30 to mean) to find the Z score. Insert into equation and solve. Remember to double to represent each side.