IGNOU probability
posted by Dharmenra on .
Among the examinees in an examination 30%, 35% and 45% failed in Statistics, in Mathematics, and in at least one of the subjects respectively. An examinee is selected at random. Find the probabilities that
a. He failed in Mathematics only
b. He passed in Statistics, if it is known that he has failed in Mathematics

Make a Venn diagram.
5% fail math only
25% fail both
10% fail stats only
60% pass both.
Of the 30% (of all students) who failed math, 5/6 of that group (25% of all students)failed stats also. That is a conditional probability of 83.3%. Only 16.7% of the mathfailing group pass stats. 
as u hve explained everything but i didn't get that 45% failed in atleast 1 of the subject but if we add
(5+25+10)% then we get only 40% which should be 45%.....plz explain