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

Problem: what is the diagonal of a square field whose perimeter is 64 m ?
16 2 m

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

Problem: 8 men , working 8 hours a day can complete a work in 18 days . how many hours a day must 12 men work to complete the same work in 12 days ?
8