Compound Interest
- The simple interest for certain sum in 2 yr at 4% pa is ₹ 80. What will be the compound interest for the same sum, if conditions of rate and time period are same ?
-
View Hint View Answer Discuss in Forum
Given, n = 2 yr, R = 4% and SI = 80
According to the formula,
CI = SI(1 + 4/200)Correct Option: B
Given, n = 2 yr, R = 4% and SI = 80
According to the formula,
CI = SI(1 + 4/200) = 80 x 51/50 = ₹ 81.60
- A sum invested for 3 yr compounded at 5%, 10% and 20% respectively. In 3 yr, if the sum amounts to ₹ 16632, then find the sum.
-
View Hint View Answer Discuss in Forum
Let the required sum be P Then,
P (1 + 5/100) (1 + 10/100) (1 + 20/100) = 16632Correct Option: B
Let the required sum be P Then,
P (1 + 5/100) (1 + 10/100) (1 + 20/100) = 16632
⇒ P x (105/100) x (110/100) x (120/100) = 16632
⇒ P = 16632 x [(100 x 100 x 100) / (105 x 110 x 120)]
∴ P = ₹ 12000
- A man borrows ₹ 5100 to be paid back with compound interest at the rate of 4 % pa by the end of 2 yr in two equal yearly installments. How much will each installment be ?
-
View Hint View Answer Discuss in Forum
Let each installment be ₹ N .
Then , according to the question ,
N/(1 + 4/100 ) + N/(1 + 4/100 )2 = 5100
⇒ 25N/26 + 625N/676 = 5100
⇒ 1275N = 5100 x 676Correct Option: A
Let each installment be ₹ N .
Then , according to the question ,
N/(1 + 4/100 ) + N/(1 + 4/100 )2 = 5100
⇒ 25N/26 + 625N/676 = 5100
⇒ 1275N = 5100 x 676
∴ N = (5100 x 676)/1275 = ₹ 2704
- What amount will be received on a sum of ₹ 1750 in 21/2 yr, if the interest is compounded at the rate of 8% pa?
-
View Hint View Answer Discuss in Forum
Given, P = ₹ 1750, R = 8%,
n = 2 and a/b = 1/2
According to the formula,
Amount = P(1 + R/100)n x [1 + {(a/b) x R}/100]Correct Option: B
Given, P = ₹ 1750, R = 8%,
n = 2 and a/b = 1/2
According to the formula,
Amount = P(1 + R/100)n x [1 + {(a/b) x R}/100]
=1750 (1 + 8/100 )2 [1 + {(1/2) x 8} /100]
=1750 (27/25)2 x 26/25
= 1750 x (27/25) x (27/25) x (26/25)
=₹ 2122.848
= ₹ 2122.85
- During the first year, the population of a village is increased by 5% and the second year, it is diminished by 5%. At the end of the second year, its population was 47880. What was the population at the beginning of the first year ?
-
View Hint View Answer Discuss in Forum
Let the population at the beginning of the first year be N .
Then, according to the question,
N x [1+ 5/100] x [1 - 5/100] = 47880Correct Option: B
Let the population at the beginning of the first year be N .
Then, according to the question,
N x [1+ 5/100] x [1 - 5/100] = 47880
⇒ N x (105/100) x (95/100) = 47880
∴ N = 47880 x (100/105) x (100/95) = 48000
