The task is to generate the correct answer for a given math problem.

Problem: the ratio of the radius of two circles is 1 : 3 , and then the ratio of their areas is ?
1 : 9

Problem: a bullet train covers a distance in 50 min , if it runs at a speed of 48 kmph on an average . the speed at which the bullet train must run to reduce the time of journey to 40 min will be .
60 kmph

Problem: how many integers n are prime numbers in the range 200 < n < 220 ?

1