If a prime number is less than 31, what is the probability that it is also less than 19.

Prime Numbers less that 31 are : 2, 3 ,5 ,7, 11, 13, 17, 19, 23, 29
n(Prime Numbers less that 31) = 10

Prime Numbers less that 31 are : 2, 3 ,5 ,7, 11, 13, 17
n(Prime Numbers less that 19) = 7

P(less than 31 but also less than 19) = 7/10