Question

if simple interest for a sum of rs 3100 for 4 years is rs 40 more than the simple interest of rs 2900 for the same duration at the same rate of interest then the rate of interest is

Answer 1

$i1 = \frac{3100 \times r \times 4}{100} = 124r \\ i2 = \frac{2900 \times r \times 4}{100} = 116r \\ i1 = i2 + 40 \\ 124r = 116r + 40 \\ 8r = 40 \\ r = 5\%$

Answer 2

Answer: The rate of interest is 5%.

Step-by-step explanation:

Let the rate of simple interest be r.

If Principal amount = Rs. 3100

Number of years = 4 yrs

If Principal amount = Rs. 2900

Their simple interest of former is Rs 40 more than the latter.

So, According to question, it becomes,

$\frac{3100\times 4\times r}{100}-\frac{2900\times 4\times r}{100}=Rs.40\\\\124r-116r=40\\\\8r=40\\\\r=\frac{40}{8}\\\\r=5\%$

Hence, the rate of interest is 5%.