Tuesday, December 20, 2011

question on normal distribution

if the mean mark is 75 with a sd of 8 marks, what should you score to be in the top 25% .

z = (x - 75) / 8 is the standard normal variate

we have to find k so that

P[X > k ] = 0.25

P[ z > (k-75)/8 ] = 0.25

refer standard normal tables (note that probability is given)

(k-75)/8 = 0.675 (approximately)

k = 80.4 marks approximately

please leave your comments below
index of math problems

There is no guarantee about the data/information on this site. You use the data/information at your own risk. You use the advertisements displayed on this page at your own risk.We are not responsible for the content of external internet sites. Some of the links may not work

No comments:

Post a Comment

please leave your comments