Compound Interest - Study Mode

[#146] The compound interest (compounded annually) on a sum of money invested for three years yields Rs. 800 and Rs. 840 in four years. The annual percentage rate of interest is:
Correct Answer

(C) 5%

Explanation

Solution: Interest of 1 year = 840 - 800 = 40 Rate = $$frac{{40}}{{50}}$$xa0× 100 = 5% Answer

[#147] The compound interest on a sum of Rs. 20,000 at 15% p.a., for $$2frac{2}{3}$$xa0years, interest compounded yearly is:
Correct Answer

(D) Rs. 9,095

Explanation

Solution:

[#148] The difference between the compound interest on a sum of Rs. 8,000 for 1 year at the rate of 10% per annum, interest compounded yearly and half yearly is:
Correct Answer

(A) Rs. 20

Explanation

Solution: Principal = Rs. 8000 Rate = 10% p.a. = 5% half per yearly Time = 1 year Compound interest yearly = $$frac{1}{{10}}$$ = Rs. 800 10 unit ⟶ Rs. 8000 1 unit ⟶ Rs. 800 Compound interest half yearly = $$frac{1}{{20}}$$ 400 unit ⟶ 8000 1 unit ⟶ 20 41 unit ⟶ 20 × 41 = Rs. 820 Difference = 820 - 800 = Rs. 20

[#149] If the difference between the compound interest and simple at 17% on a sum money for 2 years (compounded annually) is Rs. 433.50, then the compounded interest (in Rs.) is:
Correct Answer

(C) 5,533.50

Explanation

Solution: $$eqalign{
& { ext{CI}} - { ext{SI}} = frac{{17 imes 17}}{{100}} = 2.89\% cr
& 2.89\% o 433.50 cr
& 1\% o 150 cr
& 100\% o 15000 cr
& { ext{CI}} = 17 + 17 + 2.89 = 36.89\% cr
& 36.89\% o 150 imes 36.89 = 5533.50 cr} $$

[#150] A certain some of money and Rs. 2420 in 2 years and Rs. 2662 in 3 years at same rate of compound interest, compounded annually. The rate of interest per annum is = ?
Correct Answer

(D) 10%

Explanation

Solution: $$eqalign{
& { ext{Amount after three years}} cr
& { ext{ = Rs. 2662}} cr
& { ext{Amount after two years}} cr
& { ext{ = Rs. 2420}} cr
& { ext{Net interest earned in the }}{{ ext{3}}^{{ ext{rd}}}}{ ext{ year}} cr
& { ext{ = }},{ ext{2662}} - { ext{2420}} cr
& { ext{ = Rs}}{ ext{. 242}} cr
& { ext{Rate of interest (r)}} cr
& { ext{ = }}frac{{242}}{{2420}} imes { ext{100 = 10% }} cr} $$ (∴ 2 nd year's amount is principal for 3 rd year)