A sum of money invested for 3 years interest being compounded annually the rates for the successive years were 10% 15% and 18% respectively. if the compound interest for the second year amounted to 4950 find the sum invested

let principal be x
interest for first year = (prt)/100
= (x * 10* 1)/100
=x/10
amount for fist year = principal for second year= x + x/10= 11x/10
interest for second year = (prt)/100
= (11x/10 * 1*15)/100
= 33x/200
we know,
33x/200=4950
x= 4950*200/33
x=30000
the sum invested is Rs. 30000