The interest compounded annually on a sum at a rate of 10% per annum after 2 years is 3 times the interest compounded annually on another sum at a rate of 20% per annum after 3 years. Find the ratio of their sums.
1
38 : 3
2
47 : 4
3
52 : 5
4
61 : 6
5
75 : 7