The difference between C.I. and S.I. on a certain sum of money at 15% per annum for 2 years 219 days is Rs 2,061. Find the principal.
219 days = 219/365 = 3/5 years. Total time = 2 + 3/5 = 13/5 years. Rate for 2 years: 15% per year, for fractional 3/5 year rate = 15% * 3/5 = 9%. Effective CI - SI difference = P * 2061/40000 = Rs 2061 => P = Rs 40,000.
Correct Answer: Option A.
The simple interest on a certain sum at the end of three years at 5% p.a. is Rs 1,200. The compound interest on the same sum for the same period at the same rate is:
SI for 3 years at 5% = 15% = Rs 1,200 => Principal P = 1200 / 0.15 = Rs 8,000. CI for 3 years at 5% = 15.7625%. CI = 8000 * 15.7625% = Rs 1,261.
Correct Answer: Option B.
The compound interest on a certain sum of money at 8% per annum for 3 years is Rs 4,058. Find the simple interest on the same sum for 4 years at 10% p.a.
Rate = 8% = 2/25. Ratio (27/25)^3 = 19683/15625. CI factor = (19683 - 15625)/15625 = 4058 / 15625. Given CI = 4058 => Principal P = Rs 15,625. SI for 4 years at 10% = 40% of 15,625 = Rs 6,250.
Correct Answer: Option B.
If the difference between C.I. and S.I. for three years is Rs 840 and the rate of interest is 11(1/9)%, then find the principal.
Rate = 1/9. Let P = 9^3 = 729 units. CI - SI for 3 years = 3a + 1 where a = 9, so 3(9) + 1 = 28 units. 28 units = Rs 840 => 1 unit = Rs 30. Principal P = 729 * 30 = Rs 21,870.
Correct Answer: Option A.
If the difference between C.I. and S.I. for 1.5 years is Rs 1,500 at 25% per annum interest compounded half-yearly, then find the principal.
Half-yearly rate = 25/2% = 12.5% = 1/8. Time = 3 half-years. Let P = 8^3 = 512 units. CI - SI for 3 half-years = 3(8) + 1 = 25 units. 25 units = 1500 => 1 unit = 60. Principal P = 512 * 60 = Rs 30,720.
Correct Answer: Option A.