Question

Veeru invested Rs 10000 at 5% simple annual interest, and exactly after two years, Joy invested Rs 8000 at 10% simple annual interest. How many years after Veeru’s investment, will their balances, i.e., principal plus accumulated interest, be equal?

Answer 1

Let after \(n\) years both the sums amount to the equal amounts.
Then, \(1000\bigg(\frac{1+5×(n+2)}{100}\bigg) = 800\bigg(1+10×\frac{n}{100}\bigg)\)

i.e., \(1.5 = \frac{15n}{100} ⇒ n =10\)

Hence 12 years after veeru invested their balances will be equal.

Answer 2

We know that, Simple Interest =\(\frac{P∗R∗T}{100}\)

Veeru's per year interest = \(\frac{10000∗5∗1}{100} =500\)

Joy's per year interest = \(\frac{8000∗10∗1}{100} =800\)

Difference between Joy's interest and veeru's interest =300.
Initially veeru invested for 2 years, Interest for 2 years = Rs.1000
Difference between veeru's and Joy's initial amount =2000
Therefore, total Rs 3000 needs to be covered, it can be covered in 3000/300 from joys joining date= 10 years from joy's investment date

Veeru invested for 2 more years, hence total year =10+2 = 12