Directions: Answer the following practice questions as per the best of your judgment. These questions are based on simple interest.

Q.1.If Rs. 4 becomes Rs. 10 in 50 years at simple interest, the rate % p.a. is

a) 5 %

b) 2 1/2 %

c) 3 1/3 %

d) 3 %

e) 6 %

Sol : Option D Explanation: SI = 10 – 4 = 6 therefore, 6 = (4xRx50)/100 → R = 3 %.

Q.2. Find out the capital required to earn a monthly interest of Rs. 210 at 7 % simple interest.

a) Rs. 24000

b) Rs. 30000

c) Rs. 18000

d) Rs. 36000

e) Rs. 72000

Sol : Option D Explanation: 210 = (Px7x1)/100x12 → P = 36000

Q.3. If Rs. 460 amounts to Rs. 640 in 6 years, what will it amount to in 2 years at the same rate %?

a) Rs.520

b) Rs. 585

c) Rs. 700

d) Rs. 640

e) Rs. 685

Sol : Option A Explanation: Interest for 6 years = 640 – 460 = Rs.180
therefore, Interest for 2 years = (180/6)x2 = Rs.60
therefore, 460 will become 460 + 60 = Rs. 520 after 2 years

Q.4.A certain sum of money amounts to 7/4 of itself in 3 years. The rate percent p.a. is

a) 25 %

b) 20 %

c) 15%

d) 10 %

e) 5 %

Sol : Option A Explanation: R=[100(x-1)]/t % therefore, R = [100(7/4-1)]/3 = 25%

Q.5.In what time will Rs. 25 become Rs. 37 at % p.a. simple interest?

a) 1/2 Years

b) 2 Years

c) 2 1/4 Years

d) 2 1/2 Years

e) 3 Years

Sol : Option E Explanation: Interest =37 – 25 = 12 → 12 = (25/100)x16xT → T = 3 years

Q.6.The simple interest on a sum of money is of the principal and the number of years is equal to the rate % p.a. The rate % p.a. is

a) 5 %

b) 2 1/3%

c) 10 %

d) 9 %

e) 3 1/3%

Sol : Option A Explanation: = P/4 =(PxRxR)/100 → R^{2} =25% → R = 5%

Q7.A moneylender lends Rs. 60 and collects Rs. 66 at the end of four months. The rate of interest p.a. is

a) 5 %

b) 10 %

c) 20 %

d) 30 %

e) 9 %

Sol : Option D Explanation: Interest = 66 – 60 = 6 therefore, 6 = 60/100 x R x 4/12 ⇒ R= 30%.

Q8.A four year Indira Vikas certificate with a maturity value of Rs. 700 is purchased for Rs. 500.
The rate % p.a. is

a) 15 %

b) 7 1/2 %

c) 5 %

d) 10 %

e) 7 %

Sol : Option D Explanation: Interest = 200 ⇒ 200 = (500 x R x 4)/100 ⇒ R = 10 %.

Q9.In what time period will Rs. 10,000 earn an interest of Rs. 2,000 at 10 % p.a.?

a) 2 years

b) 5 years

c) 6 years

d) 3 years

e) 7 years

Sol : Option A Explanation: 2000 = (10,000x10xT)/100
T = 2 years

Q10.Anoop borrowed Rs. 800 at 6 % p.a. & Rs. 1200 at 7 % p.a. for the same duration. He had to pay Rs. 1584 in all as interest. Find the time period.

a) 10 years

b) 11 years

c) 12 years

d) 13 years

e) 15 years

Sol : Option C Explanation: Interest at 1^{st} rate for 1 year = 800 x (6x1)/100 = Rs. 48.
Interest for 1 year at 2^{nd} rate = 1200 x (7 x 1)/100 = Rs. 84
therefore, Total interest for 1 year = Rs. 132.
Hence, the required time = 1584/132 = 12 years.