Compound Interest Problems for SSC CGL

-4.

There is 80% increase in an amount in 8 years at simple interest. What will be the compound interest of Rs. 14,000 after 3 years at the same rate?

   A.) Rs.4612
   B.) Rs.4634
   C.) Rs.3794
   D.) Rs.3714

Answer: Option 'B'

Let P = Rs.100 
Simple Interest = Rs. 80 ( ∵ 80% increase is due to the simple interest)
Rate of interest = (100 × SI)/PT = (100 × 80)/(100 × 8) = 10% per annum
Now let's find out the compound interest of Rs. 14,000 after 3 years at 10%
P = Rs.14000
T = 3 years
R = 10%
Rate of interest = (100 × SI)/PT = (100 × 80)/(100 × 8) = 10% per annum
Amount after 3 years = P(1+R/100)T = 14000(1+ 10/100)3
= 14000(110/100)3 = 14000(11/10)3 = 14 × 113 = 18634
Compound Interest = Rs.18634 - Rs.14000 = Rs.4634

-3.

What is the difference between the compound interests on Rs. 5000 for 11⁄2 years at 4% per annum compounded yearly and half-yearly?

   A.) Rs. 2.04
   B.) Rs. 4.80
   C.) Rs. 3.06
   D.) Rs. 8.30

Answer: Option 'A'

Amount after1 1⁄2 years when interest is compounded yearly
= 5000 × (1 + 4/100)1 × [1+(1/2 ×4)/100] = 5000 × 104/100 × (1+2/100)
= 5000 × 104/100 × 102/100 = 50 × 104 × 51/50
= 104 × 51 = Rs. 5304
Compound Interest for 1 1/2 years when interest is compounded yearly
= Rs.(5304 - 5000)
Amount after 1 1/2 years when interest is compounded half-yearly
Compound Interest for 1 1/2 years when interest is compounded half-yearly
= Rs.(5306.04 - 5000)
Difference in the compound interests = (5306.04 - 5000) - (5304 - 5000) = 5306.04 - 5304 = Rs. 2.04

-2.

A bank offers 5% compound interest calculated on half-yearly basis. A customer deposits Rs. 1600 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest is:

   A.) Rs. 120
   B.) Rs. 121
   C.) Rs. 123
   D.) Rs. 122

Answer: Option 'B'

Rs. 121

-1.

The difference between simple and compound interests compounded annually on a certain sum of money for 2 years at 4% per annum is Re. 1. The sum is:

   A.) Rs.525
   B.) Rs.625
   C.) Rs.645
   D.) Rs.600

Answer: Option 'B'

​Rs.625

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