Question

The average GRE score at the University of Pennsylvania for the incoming class of 2016-2017 was 311. Assume that the standard deviation was 13.4. If you select a random sample of 40 students, what is the probability that the sample mean will be less than 313? Round your answer to three decimal places.

The average GRE score at the University of Pennsylvania for the incoming class of 2016-2017 was 311. Assume that the standard deviation was 13.4. If you select a random sample of 40 students, what is the standard error of the mean? Round your answer to three decimal places.

Answer 1

solution :

Given that ,

mean = = 311

standard deviation = = 13.4

n = 40

=   = 311

= / n = 13.4 / 40 = 2.119

P( <313 ) = P(( - ) / < (313 - 311) / 2.119)

= P(z < 0.94 )

Using z table

= 0.8264

mean = = 311

standard deviation = = 13.4

n = 40

=   = 311

= / n = 13.4 / 40 = 2.119