8
Q:

# Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, what was the rate of interest?

 A) 3.6 B) 6 C) 18 D) Cannot be determined

Explanation:

Explanation:

Let rate = R% and time = R years.

Then, $\inline \fn_cm \left ( \frac{1200\times R\times R}{100} \right )=432$

$\inline \fn_cm \Rightarrow 12R^{2}=432$

$\inline \fn_cm \Rightarrow R^{2}=36\Rightarrow R=6$

Q:

The minimum number of half years in which a sum of money kept at 60% compound interest will be quadrupled is ?

 A) 2 B) 4 C) 3 D) 6

Explanation:

Let us assume Amount be 100 Rs and we calculate in CI

First year 60% of 100 = 60 amount (100+60) is 160

Second year 60% of 160 = 96 amount (160+96) is 256

Third year 60% of 256 =153.6 amount (256+153.6) is 409.6

Here the Amount of 100 Rs is quadrapled in 3 years.

One year contains 2 half years

Three year has 6 half years.

$\inline \fn_jvn \small \therefore$ It takes 6 half years.

7 148
Q:

A certain sum is to be divided between A and B so that after 5 years the amount received by A is equal to the amount received by B after 7 years. The rate of interest is 10%, interest compounded annually. Find the ratio of amounts invested by them.

Let the sum(principal) received by A and B are x and y.

(1+r) = $\inline \fn_jvn 1+\frac{1}{10}$ =$\inline \fn_jvn \frac{11}{10}$

Then, $\inline \fn_jvn \frac{x}{y}=\left ( \frac{11}{10} \right )^{7-5}$ =$\inline \fn_jvn \left ( \frac{11}{10} \right )^2 =\frac{121}{100}$

Hence, the ratio in which the sum is divided =121:100

796
Q:

A sum is being lent at 20 % per annum compound interest.what is the ratio of increase in amount of 4th year to 5th year?

 A) 4:5 B) 5:4 C) 5:6 D) can't be determined

Explanation:

$\inline&space;\frac{p\left&space;(&space;1+\frac{r}{100}&space;\right&space;)^4}{p\left&space;(&space;1+\frac{r}{100}&space;\right&space;)^5}=\frac{1}{\left&space;(&space;1+\frac{r}{100}&space;\right&space;)}$

= $\inline&space;\frac{100}{100+r}=\frac{100}{120}$  = $\inline&space;\frac{5}{6}$

22 950
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 = $\inline&space;\frac{2250\times&space;50\times&space;1}{100}=1125$

5 1208
Q:

What is the SI on Rs.2500/- at the rate of 12% per annum for 8 years?

 A) 2200 B) 2300 C) 2400 D) 2500