During every financial year, the value of a machine depreciates by 12%. Find the original cost of a machine which depreciates by ₹ 2640 during the second financial year of its purchase.

Find the sum on which the difference between the simple interest and the compound interest at the rate of 8% per annum compounded annually be ₹ 64 in 2 years.

Saurabh invests ₹ 48000 for 7 years at 10% per annum compound interest. Calculate :

(i) the interest for the first year.

(ii) the amount at the end of second year.

(iii) the interest for the third year.

Ashok borrowed ₹ 12000 at some rate per cent compound interest. After a year, he paid back ₹ 4000. If compound interest for the second year be ₹ 920, find :

(i) the rate of interest charged

(ii) the amount of debt at the end of the second year.