Question

Recent test scores on the Law School Admission Test (LSAT) are normally distributed with a mean of 162.4 and a standard deviation of 15.9. What is the probability that the mean of 12 randomly selected scores is less than 161?

0.535

0.620

0.380

0.465

Answer 1

Solution :

Given that ,

mean = = 162.4

standard deviation = = 15.9

n = 12

= 101 and

= / n = 15.9 / 12

P( < 161) = P(( - ) / < (161 - 162.4) / 15.9 / 12 ) = P(z < -0.305)

Using standard normal table,

P( < 161) = 0.380

Probability = 0.380