CTS Company Numerical Ability Number System

Two distinct no s are taken from 1,2,3,4......28 Find the probability that their sum is less than 13

Read Solution (Total 1)

There are 28C2*2! = 378 pairs of numbers that are possible.

The pairs that sum to less than 13 are

1 + 2
1 + 3
...
1 + 11 (10)
We skip 2 + 1, because it's the same as 1 + 2
2 + 3
..
2 + 10 (8)
3 + 4
..
3 + 9 (6)
4 + 5
..
4 + 8 (4)
5 + 6
5 + 7 (2)

For a total of 30 pairs.

30/378
10 years agoHelpfull: Yes(2) No(3)

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