A person invested a sum of Rs. 18,600 at x% p.a and another sum that is twice the former at (x + 2)% p.a., both at simple interest. If the total interest earned on both investments for \(3\frac{1}{2}\) years is Rs. 23, 110.50, then the rate of interest p.a. on the second investment is:
1
135
2
11%
3
10.55
4
12.5%