P = Rs 12000

R = 6% per annum

T = 2 years

To find the compound interest, the amount (A) has to be calculated.

∴ C.I. = A − P = Rs 13483.20 − Rs 12000 = Rs 1,483.20 C.I. − S.I. = Rs 1,483.20 − Rs 1,440 = Rs 43.20 Thus, the extra amount to be paid is Rs 43.20.