Simple And Compound InterestPage 1
1.  Find the interest under simple interest for a principal of ₹1200 at an interest rate of 5% per annum for a period of 4 years.  (a)240  (b)260  (c)320  (d)450 

Answer is: AI = PNR/100
Here, P = 1200
N = 4
R = 5%
I = (1200 x 4 x 5)/100 = ₹240.
I = ₹240.
2.  What is the interest earned on ₹10,000 for 2 years at 10% per annum simple interest?(in ₹)  (a)2000  (b)1500  (c)2500  (d)3000 

Answer is: AI = PNR/100
I = (10000 x 2 x 10)/100
I = 2000.
3.  What is the interest earned on ₹10000 for 2 years at 10% per annum compound interest, compounded annually?  (a)210  (b)420  (c)315  (d)630 

Answer is: AInterest for the first year
= (1000 x 1 x 10)/100 = 100
Principal for second year
= 1000 + 100 = 1100
Interest for the second year = (1100 x 1 x 10)/100 = 110
Hence, Total interest for the two years = 100 + 110 = ₹210.
4.  If ₹2000 amount to ₹2200 in 2 years under simple interest, what is the rate of interest per annum?  (a)15%  (b)10%  (c)5%  (d)20% 

Answer is: CI = Amount  Principal = 2200  2000 = ₹200.
I = PNR/100
200 = (2000 x 2 x R)/100 = 5%
5.  If ₹20000 amount to ₹24200 in 2 years under compound interest, what is the rate of interest per annum?  (a)10%  (b)20%  (c)15%  (d)Cannot be determined 

Answer is: AA = P(1 + R/100)^N
24200 = 20000(1 + R/100)^2
1.21 = (1 + R/100)^2
R = 10%
6.  What is the interest earned in the first year on ₹200 at 10% per annum compound interest, interest compounded every 6 months?  (a)₹20  (b)₹20.50  (c)₹25  (d)₹23.20 

Answer is: BInterest for first six months = (200 x 1/2 x 10)/100 = ₹10
Principal for next six months = 200 + 10 = ₹210
Interest for next six months = (210 x 1/2 x 10)/100 = ₹10.5
Total interest = 10 + 10.5 = ₹20.5
7.  At what rate percent per annum will a sum of money double in 16 years?  (a)6  (b)13/2  (c)25/4  (d)31/5 

Answer is: CLet principal = P.
Then, S.I. = P
And T = 16 years.
R = (100 x P)/(P x 16)% = 25/4% p.a.
8.  A sum of ₹1550 is lent out into two parts, one at 8% and another one at 6%. If the total annual income is ₹106, find the money lent at each rate.  (a)800  (b)900  (c)1000  (d)700 

Answer is: BLet the sum lent at 8% be ₹ X and that at 6% be ₹ (1550  X).
[8 x 1 x X]/100 + [(1550  X) x 6 x 1]/100 = 106
8X + 9300  6X = 10600
2X = 1300
X = 650
Money lent at 8% = ₹650.
Money lent at 6% = ₹(1550  650) = ₹900.