Find the number z such that the proportion of observations t

Find the number z such that the proportion of observations that are less than z in a standard Normal distribution is 0.65.

Find the number z such that 25% of all observations from a standard Normal distribution are greater than z.

Solution

A )

Refer link : http://de.wikipedia.org/wiki/Tabelle_Standardnormalverteilung

Find there 0.65 and see which z belong to it
z= 0.38 sigma


B) Find there 0.75 ( difference from 1 - 0.25)
z = 0.67
answer is z= -0.67