Three numbers are chosen from 1 to 20. The probability that they are not consecutive is

3 numbers can be chosen out of 20 in 20C3 ways.


As we have to choose 3 consecutive numbers. So we can’t choose 19 and 18.


Choosing consecutive number is same as choosing a single number because other 2 numbers are automatically chosen.


This can be chosen 18 ways.


P(chosen numbers are consecutive) =


Our answer matches with option (d)


Option (d) is the only correct choice

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