Question

9. A certain sum of money trebles itself in
5 years simple interest. Find the rate of interest per
annum.​

Answer 1

Answer:20% per annum

Step-by-step explanation:

Answer 2

Answer:

40% is the rate of interest per annum.

Solution:

Let the Principal be denoted as P.

Let the rate of interest be denoted in % as r

Let the number of years be denoted as n.

Given the principle amount triples itself in 5 years.

Hence n = 5, amount = 3P

Simple interest $=\frac{\mathbf{p} \times \mathbf{n} \times \mathbf{r}}{100}$

Since 3P = P + Pnr (since r is in terms of percentage)

3P $=P(1+(5 \times r))$

3 = 1 + 5r

2 = 5r

r = 0.4 = 40%.

Result:

The rate of interest per annum is 40%.