Question

For a normal distribution given a standard deviation of 3.8 in a mean of 54 what percent lies above 48

A 0.1690
B 0.0571
C 0.7660
D 0.9429

Answer 1

choice D.) 0.9429

Explanation:

Given a Normal data set

mean u = 54

standard deviation s = 3.8

we want P( X > 48)

Standardize this probability so we can use Z-scores.

P( X > 48) = P( (X - u)/s > (48 - 54)/3.8 ) = P(Z > -1.5789)

so I look for P ( Z > 1.5789) = 0.0571

so P(Z > -1.5789) = 1 - P(Z > 1.5789) = 1 - 0.0571 = 0.9429