Question

1. The simple interest on Rs. 400 for 5 years together with than on Rs.600 for 4 years came to
Rs.132, the rate being the same in both cases. Find the rate of interest ?
a) 5%
b) 4%
c) 6 12 %
d) 3%​

Answer 1

Answer:

3%

Step-by-step explanation:

400*5*R/100 + 600*4*R /100 =132

20R + 24 R = 132

44R =132

R = 3 %

Answer 2

Given,

Amount, $\[\left( {{p_1}} \right) = 400Rs\]$

Time, $\[\left( {{t_1}} \right) = 5\,years\]$

Amount, $\[\left( {{p_2}} \right) = 600Rs\]$

Time, $\[\left( {{t_2}} \right) = 4years\]$

Interest $\[ = 132Rs.\]$

Solution,

Calculate the rate of interest.

$\[132 = \frac{{400 \times r \times 5}}{{100}} + \frac{{600 \times r \times 4}}{{100}}\]$

$\[ \Rightarrow 13200 = 2000r + 2400r\]$

$\[ \Rightarrow 13200 = 4400r\]$

$\[ \Rightarrow r = \frac{{13200}}{{4400}}\]$

$\[ \Rightarrow r = 3\% \]$

Hence the rate of interest is $\[3\% \]$.

Hence the correct option is (d), i.e. $\[3\% \]$