8
Q:

# Rs 1000 is being  charged at 50% per annum. what is the interest for 3rd year at compound interest?

 A) 1122 B) 1025 C) 1125 D) 625

Explanation:

Total amount for two years = $\inline&space;1000(1.5)^2=2250$

Now , interest for third year = $\inline&space;\frac{2250\times&space;50\times&space;1}{100}=1125$

Q:

Compound interest earned on a sum for the second and the third years are Rs.1200 and Rs.1440 respectively. Find the rate of interest ?

 A) 20% p.a B) 15% p.a C) 18% p.a D) 24% p.a

Explanation:

Rs.1440 - 1200 = Rs.240 is the interest on Rs.1200 for one year.

Rate of interest = (100 x 240) / (1200) = 20% p.a

1 29
Q:

In what time will Rs. 3300 becomes Rs. 3399 at 6% per annum interest compounded half-yearly ?

 A) Quarter months B) Half year C) 2 years D) 1 year

Explanation:

3300 ----- 3% ↑ (1st time interval, 99) → 3399.

Here, time interval is given as half-yearly i.e. 6 months.

1 82
Q:

Find the principal if the interest compounded at the rate of 10% per annum for two years is Rs. 420 ?

 A) Rs. 2000 B) Rs. 2100 C) Rs. 1900 D) Rs. 2150

Explanation:

Given,
Compound rate, R = 10% per annum
Time = 2 years
C.I = Rs. 420
Let P be the required principal.
A = (P+C.I)
Amount, A = {$\inline \fn_jvn \small P[1+ (R/100)]^{n}$}
(P+C.I) = {$\inline \fn_jvn \small P[1+10/100]^{2}$}
(P+420) = P[11/10][11/10]
P-1.21P = -420
0.21P = 420
Hence, P = 420/0.21 = Rs. 2000

1 70
Q:

Sonika invested an amount of Rs.5800 for 2 years. At what rate of compound interest will she get an amount of Rs.594.50 at the end of 2 years ?

 A) 6.5% B) 6% C) 5% D) 4.5%

Explanation:

C.I = $\inline \fn_jvn \small P\left [ \left ( 1+\frac{r}{100} \right )^{t}-1 \right ]$

594.5 = $\inline \fn_jvn \small 5800\left [ \left ( 1+\frac{r}{100} \right )^{2} -1\right ]$

$\inline \fn_jvn \small \frac{594.5}{5800}+1=\left ( 1+\frac{r}{100} \right )^{2}$

$\inline \fn_jvn \small \frac{r}{100}=1.05-1=0.05\Rightarrow r=5$ % .

4 237
Q:

The compound interest on a certain sum for 2 years at 10% per annum is Rs. 1155. The simple interest on the same sum for double the time at half the rate percent per annum is ?

 A) Rs. 1100 B) Rs. 5500 C) Rs. 1400 D) Rs. 4120

Explanation:

Let the sum be Rs.x. Then,

$\inline \fn_jvn \small \left [ x\left ( 1+\frac{10}{100} \right )^{2}-x \right ]=1155$

$\inline \fn_jvn \small \Rightarrow x\left [\left ( \frac{11}{10} \right )^{2}-1 \right ]=1155$

=> x =5500

sum = Rs. 5500.

So, S.I = Rs. $\inline \fn_jvn \small \left ( \frac{5500x5x4}{100} \right )=Rs. 1100$