A certain sum of money becomes Rs. 1000 in 2 years and Rs. 1100 in 4 years at simple rate of interest. The rate of interest per annum is
5 5/9 %
Under Simple Interest, the amount grows by a fixed sum every year, so equal time-gaps produce equal interest amounts.
SI for 2 years (year 2 to year 4) = Rs. 1100 − Rs. 1000 = Rs. 100 ⇒ SI per year = Rs. 50.
Principal (P) = Amount at end of 2 years − SI for those 2 years = 1000 − 100 = Rs. 900.
Rate (R) = (50 ÷ 900) × 100 = 50/9 = 5 5/9 % per annum.
Important Questions from Simple Interest
Anil lent a sum of Rs. 5,000 on simple interest for 10 years in such a way that the rate of interest is 6% per annum for the first 2 years, 8% per anmum for the next 2 years and 10% per annum beyond 4 years. How much interest (in Rs.) will he earn at the end of 10 years?
What will be the simple interest on a sum of Rs. 12000 at the rate of 15 percent per annum for three years ?
If in 13 years fixed sum doubles at simple interest, what will be the interest rate per year? (correct to two decimal places)
On simple interest a sum of Rs. 640 becomes Rs. 832 in 2 years. What will Rs. 860 become in 4 years at the same rate of simple interest?
A certain sum amounts to Rs. 81840 in 3 years and to Rs. 92400 in 5 years at x% p.a. under simple interest. If the rate of interest is becomes (x + 2)%, then in how many years will the same sum double itself?
