Compound Interest Questions and Answers updated daily – Aptitude
Compound Interest Questions










Investment in scheme A = Rs. x/2
According to the question,
A = P(1 + (R/100))T
x(1 + (20/100))2 - x/2(1 + (10/100))2 = 3507
x(6/5)2 - x/2(11/10)2 = 3507
36x/25 - 121x/200 = 3507
(288x - 121x)/200 = 3507
167x = 3507*200
x = (3507*200)/167
= Rs. 4200










= P[(1 + 20/100)2 - 1]
= P[(6/5)2 - 1]
= P[(36/25) - 1] = Rs. 11P/25
SI = PTR / 100
= (11P/25) * (2*7.5/100)
= Rs. 33P/500
According to the question,
33P/500 + 11P/25 = 3036
(33P + 220P)/500 = 3036
253P = 3036*500
P = (3036*500)/253 = Rs. 6000










A = P(1 + R/100)T
13392 = 9300(1 + R/100)2
13392/9300 = (1 + R/100)2
144/100 = (1 + R/100)2
(12/10)2 = (1 + R/100)2
12/10 = (1 + R/100)
R/100 = 12/10 - 1 = 2/10
R = (2/10)*100 = 20% p.a.
New rate = (R - 10)% = 10%
CI = P[(1 + R/100)T - 1]
= 9300[(1 + 10/100)2 - 1]
= 9300[(11/10)2 - 1]
= 9300(121/100 - 1)
= (9300*21)/100
CI = Rs. 1953










Time(T) = 4 Years
Rate of Interest (R) = 6% per year
To find Principal,
Formula to calculate Simple Interest:
SI = PRT/100
SI= Simple Interest; P=Principal
S.I. = (PRT)/100
1600 = (P*6*4)/100
1600*100 = P*24
(1600*100)/24 = P
P = Rs.6,667
Therefore, the sum of money is Rs.6,667.
To find compound interest (C.I.) for the same sum,
Formula for Compound Interest (C.I)
C.I. = [P*(1+R/100)N] – P
C.I. = [6667*(1+6/100)4] – 6667
C.I. = Rs. 1,750










Sum of money amounts in 2 yrs = Rs. 2420
Sum of money amounts in 3 yrs = Rs. 2662
So, interest on Rs.2420 for 1 yr = 2662 - 2420
= Rs. 242
SI = PNR/100
242 = (2420 x 1 x R)/100
R = (242 x 100)/2420
R = 10%.










Difference between CI and SI for 2 yrs = 20
PR²/100² = 20 ...(1)
Also given,
Difference between CI and SI for 3 yrs = 61
PR²/100²[(300 + R)/100] = 61
20[(300 + R)/100] = 61
300 + R = (61/20)*100
300 + R = 305
R = 5%
From (1),
P = 20*(100²/5²)
P = Rs. 8000
Therefore, sum is Rs.8000.










Difference between CI and SI for 2 yrs = 832 - 800
PR²/100² = 832 - 800
PR²/100² = 32 .......(1)
SI for 2 yrs = Rs.800
PNR/100 = 800
2PR/100 = 800 ....(2)
Divide (1) by (2),
R/200 = 32/800
R = 8%
Therefore, Principal = SI x(100/NR)
Principal = (800 x 100)/(2 x 8)
Principal = Rs. 5000
Difference between CI and SI for 3 yrs = PR²(300 + R)/100³
= (5000 x 8² x (300 + 8))/100³
= Rs. 98.56










Rate of interest for 2 yrs = 20%
Rate of interest for last one yr = 125% of 20
= (125/100)*20 = 25%
WKT, A = P[1 + (r/100)]n
According to the question,
= 15,00,000{[1 + (20/100)]2[1 + (25/100)1]} - 15,00,000[1 + (20/100)]3
= 15,00,000{[1.2]2[1.25]} - 15,00,000[1.2]3
= 15,00,000(1.8 - 1.728)
= 15,00,000 x 0.072
= Rs.1,08,000
Required percentage = (108000/1500000)*100 = 7.20%.










Therefore, Shyam share = Rs. (260200 - x)
WKT, A = P[1 + (R/100)]n
According to the question,amount recieved by Ram is same as that of Shyam,
x[1 + (4/100)]4 = (260200 - x)[1 + (4/100)]6
x = (260200 - x)[1 + (4/100)]2
x = (260200 - x)[1 + (1/25)]2
x = (260200 - x)[26/25]2
x = (260200 - x) (676/625)
(625x/676) = 260200 - x
(625x/676) + x = 260200
(625x + 676x)/676 = 260200
1301x = 260200*676
x = (260200*676)/1301
x = Rs. 1,35,200
Therefore, Ram's share is Rs. 1,35,200.










Therefore, the amount invested in the scheme B = (40000 - X).
Given that the simple and compound interest for 1st year is same.
According to the question,
15% of X = 10% of (40000 - X)
15X/100 = (400000 - 10X)/100
15X = 400000 - 10X
15X + 10X = 400000
25X = 400000
X = Rs. 16,000
Amount invested in scheme B = 40000 - X
= 40000 - 16000
= Rs. 24,000
Therefore, Rs. 24,000 invested in scheme B.










r₠= 3%; r₂ = 4%; r₃ = 5%
WKT, Amount = P[1 + (R/100)]n
A = P{(1 + (râ‚/100)) * (1 + (râ‚‚/100)) * (1 + (r₃/100))}
= 2500{(1 + (3/100)) * (1 + (4/100)) * (1 + (5/100))}
= 2500(103/100) * (104/100) * (105/100)
A = Rs. 2811.90
CI = Amount - Principal
CI = 2811.90 - 2500
CI = Rs. 311.90










Time = n = 3/2 years = 3 half years
Formula for amount, A = P(1+(r/100))â¿
= 37500 (1+(4/100))³
= 37500 (1+(1/25))³
= 37500 (26/25)³
= Rs. 42812.4
Therefore, amount A = Rs. 42812.4










WKT, Amount = P[1 + (R/100)]n
Amount = [200(1 + (5/100))3] + [200(1 + (5/100))2] + [200(1 + (5/100)]
= [200(1 + (1/20))3] + [200(1 + (1/20))2] + [200(1 + (1/20)]
= [200(21/20)3] + [200(21/20)2] + [200(21/20)]
= [(200*9261)/8000] + [(200* 441)/400] + [210]
= 231.525 + 220.5 + 210
= Rs. 662.025
Therefore amount at the end of 3 years be Rs. 662.025.










WKT, Amount = P[1 + (R/100)]n
Sum of money amounts to Rs. 4840 in 2 yr,
4840 = P[1 + (r/100)]2 ....(i)
Sum of money amounts to Rs. 5324 in 3 yr,
5324 = P[1 + (r/100)]3 .....(ii)
Dividing equation (ii) by (i), we get
5324/4840 = 1 + (r/100)
(5324/4840) - 1 = (r/100)
(5324 - 4840)/4840 = (r/100)
484/4840 = r/100
r = (484/4840)*100
r = 10%
Therefore, rate of interest per annum is 10%.
Study the following information carefully and answer the given questions:
A man invested Rs. 30000 in a scheme at 20% compound interest for 2 years. After 2 years he withdraws all his money. From that money, he purchased a Bike worth Rs. 32000. And with remaining amount, 10% in mutual funds and with the remaining money, he purchased 2 watches W1 and W2 for an equal amount. He sells watch W1 at 10% profit and watches W2 at 20% profit.
Refer the above for the Questions 55 to 54










Compound interest:
30000 * (20/100)= 6000
36000 * (20/100)= 72000
Compound Interest = 6000 + 7200
C.I = Rs.13200
The amount received after 2 years of his investment = 30000 + 13200 = Rs. 43200
It is given that, he purchased a Bike worth Rs.32000
Remaining amount = 43200 – 32000 = Rs.11200
Total amount invested in Mutual funds = 11200*(10/100) = Rs. 1120
Remaining amount = 11200 – 1120 = Rs. 10080
With this remaining amount, he purchased 2 watches W1 and W2 for an equal amount.
Cost price of W1 = Cost price of W2 = 10080/2 = Rs.5040
Selling price of W1 = 5040*(110/100) = Rs.5544
Selling price of W2 = 5040*(120/100) = Rs. 6048
Study the following information carefully and answer the given questions:
A man invested Rs. 30000 in a scheme at 20% compound interest for 2 years. After 2 years he withdraws all his money. From that money, he purchased a Bike worth Rs. 32000. And with remaining amount, 10% in mutual funds and with the remaining money, he purchased 2 watches W1 and W2 for an equal amount. He sells watch W1 at 10% profit and watches W2 at 20% profit.
Refer the above for the Questions 56 to 55










Compound interest:
30000 * (20/100)= 6000
36000 * (20/100)= 72000
Compound Interest = 6000 + 7200
C.I = Rs.13200
The amount received after 2 years of his investment = 30000 + 13200 = Rs. 43200
It is given that, he purchased a Bike worth Rs.32000
Remaining amount = 43200 – 32000 = Rs.11200
Total amount invested in Mutual funds = 11200*(10/100) = Rs. 1120
Remaining amount = 11200 – 1120 = Rs. 10080
With this remaining amount, he purchased 2 watches W1 and W2 for an equal amount.
Cost price of W1 = Cost price of W2 = 10080/2 = Rs.5040
Selling price of W1 = 5040*(110/100) = Rs.5544
Study the following information carefully and answer the given questions:
A man invested Rs. 30000 in a scheme at 20% compound interest for 2 years. After 2 years he withdraws all his money. From that money, he purchased a Bike worth Rs. 32000. And with remaining amount, 10% in mutual funds and with the remaining money, he purchased 2 watches W1 and W2 for an equal amount. He sells watch W1 at 10% profit and watches W2 at 20% profit.
Refer the above for the Questions 57 to 56










Compound interest:
30000 * (20/100)= 6000
36000 * (20/100)= 72000
Compound Interest = 6000 + 7200
C.I = Rs.13200
The amount received after 2 years of his investment = 30000 + 13200 = Rs. 43200
It is given that, he purchased a Bike worth Rs.32000
Remaining amount = 43200 – 32000 = Rs.11200
Total amount invested in Mutual funds = 11200*(10/100) = Rs. 1120
Remaining amount = 11200 – 1120 = Rs. 10080
Study the following information carefully and answer the given questions:
A man invested Rs. 30000 in a scheme at 20% compound interest for 2 years. After 2 years he withdraws all his money. From that money, he purchased a Bike worth Rs. 32000. And with remaining amount, 10% in mutual funds and with the remaining money, he purchased 2 watches W1 and W2 for an equal amount. He sells watch W1 at 10% profit and watches W2 at 20% profit.
Refer the above for the Questions 58 to 57










Compound interest:
30000 * (20/100)= 6000
36000 * (20/100)= 72000
Compound Interest = 6000 + 7200
C.I = Rs.13200
The amount received after 2 years of his investment = 30000 + 13200 = Rs. 43200
It is given that, he purchased a Bike worth Rs.32000
Remaining amount = 43200 – 32000 = Rs.11200
Study the following information carefully and answer the given questions:
A man invested Rs. 30000 in a scheme at 20% compound interest for 2 years. After 2 years he withdraws all his money. From that money, he purchased a Bike worth Rs. 32000. And with remaining amount, 10% in mutual funds and with the remaining money, he purchased 2 watches W1 and W2 for an equal amount. He sells watch W1 at 10% profit and watches W2 at 20% profit.
Refer the above for the Questions 59 to 58










Compound interest:
30000 * (20/100)= 6000
36000 * (20/100)= 72000
Compound Interest = 6000 + 7200
C.I = Rs.13200
The amount received after 2 years of his investment = 30000 + 13200 = Rs. 43200










Reet invested an amount = Rs.A
Sonali invested an amount = Rs. (A + 1500)
According to the question, same amount of interest is received by both.
Therefore, CI = SI
P[1 + (R/100)]â¿ - P = PNR/100
A(1 + (12/100))² - A = [(A + 1500)*3*8%]
A*(112/100)*(112/100) - A = (A + 1500)*(24/100)
A*(12544/10000) - A = A*(24/100) + (1500*(24/100))
A*(12544/10000) - A - A*(24/100) = 360
(12544A - 10000A - 2400A)/10000 = 360
144A = 3600000
A = Rs. 25,000
Amount invested by Reet = Rs. 25,000.