Correct Answer - B
Out of 30 numbers from 1 to 30, three numbers can be chosen in .30C3
ways.
So, total number of elementary events =.30C3
.
Three consecutive numbers can be chosen in one of the following ways :
(1,2,3),(2,3,4),..,(28,29,30)
.
∴
Number of elementary events in which three numbers are consecutive is 28.
Thus,
Probability that the numbers are consecutive =
28
.30C3
=
1
145
Hence, required probability =1-
1
145
=
144
145