Q.1 Difference between the simple interest received from two banks on Rs. 500 for two years is Rs. 2.50. What is the difference between their rates (in %) ?

A) 0.25

B) 0.5

C) 1

D) 2.5

Ans. A

Let x & y are the interest rate of two banks

Thus,

According to question,

500*x*2/100 – 500*y*2/100 = 2.50

Or 10 (x-y) = 2.50

x-y = 2.50/10

= 0.25 %

Q.2 A sum of money doubles itself in 10 yrs at S.I. What is the rate of interest ?

A) 8 %

B) 9 %

C)10 %

D) 11 %

Ans. C

Shortcut:

Time *rate=100(principal-1)

Or Rate= 100(2-1)/10

=10%

Q.3 A certain sum of money amounts to Rs.4720 in 3 yrs at 6 % p.a. S.I. In how many years will it amount to Rs.5680 at the same rate of interest ?

A) 4 yrs

B) 5 yrs

C) 6 yrs

D) 7 yrs

Ans. D

T= 1/r [ ( A2 / A1 * 100 + rt1 ) – 100]

1/6 [5680/4720 100 + 6 * 3 – 100]

1/6 [ 71/59*118-100]

=1/6 [142-100]

Or 42/6 = 7yrs

Q.4 A sum of money doubles itself in 4 yrs at S.I. In how many years will it amount to 8 times ?

A) 28 yrs

B) 29 yrs

C) 30 yrs

D) 31 yrs

Ans. A

Double in 4 yrs

Triple in 4*2=8 yrs

4 times in 4*3 = 12 yrs

5 times in 4*4 =16 yrs

6 times in 4*5 = 20 yrs

7 times in 4*6 = 24 yrs

8 times in 4*7 = 28 yrs

Q.5 Difference between C.I. & S.I. on a certain sum at 10% p.a for 2 yrs is Rs. 631. Find the sum ?

A) 63100 Rs.

B) 63200 Rs.

C) 63300 Rs.

D) 63400 Rs.

Ans. A

Shortcut :

Sum=Difference * (100/R)2

Or 631*100*100 / 10*10

=Rs. 63100