Math Is Fun Forum

EMPhillips1989

Member

Registered: 2008-01-21

Posts: 40

please help!!!!! probability!!!

marks out of 100 in an exam are normally distributed with mean 68 and variance 25

suppose the top 15% of students recieve a grade A. what is the minimum mark that a student must have to achieve to get an A??

the pass mark is 54% given that a student passed the exam, what is the probability she got an A??

please help!! if anyone could show me roughly how i would do this sort of question

Last edited by EMPhillips1989 (2008-02-27 23:38:24)

EMPhillips1989

Member

Registered: 2008-01-21

Posts: 40

Re: please help!!!!! probability!!!

what i thought i had to do for the first part is:

looking at the table this gives 0.99 which would imply the minimum mark for a grade a is 99marks this must be incorrect please can anyone help!!!!

Last edited by EMPhillips1989 (2008-02-27 23:42:52)