24
Q:

# At What rate percent per annum will a sum of money double itself is 12 years?

Q:

The interest on a certain deposit at 4.5% p.a. is Rs. 202.50 in one year. How much will the additional interest in one year be on the same deposit at 5% p.a.  ?

 A) Rs. 22.5 B) Rs. 2.5 C) Rs. 202 D) Rs. 25

Answer & Explanation Answer: A) Rs. 22.5

Explanation:

We know that I = PTR/100
=> P = 20250/4.5 = 4500
Now, new Interest at 5% = 4500x1x5/100 = 225
Now the additional amount = 225 - 202.5 = Rs. 22.5

1 1
Q:

The simple interest on Rs. 25 for 4 months at the rate of 3 paise per rupee per month is :

 A) 240 paise B) Rs. 1.40 C) Rs. 2.20 D) Rs. 3

Answer & Explanation Answer: D) Rs. 3

Explanation:

I = PTR/100
I = 25 x 4 x 0.03/100
I = 0.03 x 100 = 300 Ps = Rs. 3

1 1
Q:

A sum of money becomes 7/6 of itself in 3 years at a certain rate of simple interest. The rate per annum is ?

 A) 45/7 % B) 50/9 % C) 51/7 % D) 47/ 9 %

Answer & Explanation Answer: B) 50/9 %

Explanation:

Let sum = S. Then, amount = 7S/6

S.I. = 7S/6 - S = S/6; Time = 3 years.

Rate = (100 x S) / (S x 6 x 3) = 5 5/9 = 50/9 %.

1 16
Q:

If the C.I. on a sum for 2 years at 12 1/2 % per annum is Rs. 510, the S.I. on the same sum at the same rate for the same period of time is   ?

 A) Rs. 580 B) Rs. 480 C) Rs. 550 D) Rs. 470

Answer & Explanation Answer: B) Rs. 480

Explanation:

Let the sum be Rs. P. Then,

$\inline \fn_jvn \small \left [ P\left ( 1 +\frac{25}{2x100} \right )^{2} -P \right ]$ = 510

P[$\inline \fn_jvn \small \left ( \frac{9}{8} \right )^{2}$ - 1] = 510.

Sum = Rs. 1920

So, S.I. = (1920 x 25 x 2) / (2 x 100) = Rs. 480

2 12
Q:

A person got Rs.48 more when he invested a certain sum at compound interest instead of simple interest for two years at 8% p.a. Find the sum  ?

 A) Rs.8000 B) Rs.6500 C) Rs.7500 D) Rs.5000

Explanation:

$\fn_jvn \small P = \frac{(d x 100^{2})}{R^{2}}$
Where d is difference, r is rate of interest.

=> (48 x 100 x 100) / 8 x 8 = Rs.7500