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