A student gets 450 marks out of 500 in an exam having subject Hindi, Mathematics, Physics, Chemistry

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30 Apr 2015 Probability

A student gets 450 marks out of 500 in an exam having subject Hindi, Mathematics, Physics, Chemistry and English. For qualifying an exam of science his score should be 90% in 3 subjects Physics, Chemistry and Mathematics. Probability to get his success in that exam will be.

OPtion

1) 1/5
2) 2/5
3) 3/5
4) 4/5
5) 1/3
6) 2/3
7) 1/4
8) 3/4
9) 1/2
10)1

Solution

Number of combinations for Physics, Chemistry and Mathematics are
(5*4*3*2*1)/(3*2*1*2*1) = 10
Out of 10 combinations non-qualifying combination are
(82,85,93), (82,85,94), (82,85,96) and (82,93,94)
So possibility to get his success = 6/10
=3/5

Option 3)

Correct Option: 3 Best Solution (7)