What is the principal, if after five years at 11% p.a. simple interest, it amounts to rs 18600?

Let Principal=1, SI =PRT%. So, SI = 1 ×11/100×5 SI = 11/20. And Principal(P)=1. Amount=P+SI, Amount=1+11/20, Amount=31/20 which is equal to 18,600. So the value of 1 ratio will be12,000. So, the principal will be 12,000 and the interest will be 6,600 (11/20×12,000). So the answer will be Rs.12,000(Principal).