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