In this task, you need to provide the correct option for a given problem on probability from the provided options.

Q: Problem: how many positive integers less than 400 can be formed using the numbers 1 , 2 , 3 and 5 for the digits ? 
Options: a ) 48 , b ) 52 , c ) 66 , d ) 84 , e ) 68

A: e
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Q: Problem: there are 5 pairs of socks and 2 socks are worn from that such that the pair of socks worn are not of the same pair . what is the number of pair that can be formed . 
Options: a ) 19 , b ) 20 , c ) 30 , d ) 32 , e ) 25

A: b
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Q: Problem: a box contains 21 electric bulbs , out of which 4 are defective . two bulbs are chosen at random from this box . the probability that at least one of these is defective is 
Options: a ) 4 / 19 , b ) 7 / 19 , c ) 12 / 19 , d ) 21 / 95 , e ) 31 / 88

A:
e
****
