Question

Statistics students in Quebec Universities score 75.91 on average on a test of basic math

ability. The standard deviation of the test scores is 14.1415. If we choose 8 students at random and give

them the test, what is the exact probability that the mean of these 8 scores will be 70.00 or lower?

Answer 1

Solution :

Given that ,

mean = = 75.91

standard deviation = =14.1415

n=8

P(x < 70) = P[(x - ) / /n < (70-75.291) /14.1415/8 ]

= P(z < -1.06)

Using z table,

=0.1446

probability that the mean of these 8 scores will be 70.00 or lower=0.1446