Aptitude Day 83

Ratio and Proportion:

1. The sum of the 3 numbers is 148. If the ratio of the first to the second is 1:3 and that of the second to the third is 4:7, then the first number is:

Solution:
               Let the numbers be x, y and z.
               x:y = 1:3 and y:z = 4:7
               x:y:z = 4:12:21

               4a+12a+21a = 148.
               37a =148
               a = 4.
               The first number is 4a = 16.

2. A fraction which bears the same ratio to 3/7 that 1/9 does to 5/12, is equal to:

Solution:
               Let that fraction be x.
               x:3/7 :: 1/9: 5/12
               (3/7)*(1/9) = x*(5/12)
               x = 4/35.