# In how many years will the simple interest on a certain sum be 4.05 times the principal at 13.5 percent per annum

**Solution:**

We have to find the number of years in which the simple interest on a certain sum is 4.05 times the principal at 13.5 percent per annum.

Let the principal be P

According to the question,

Interest, I = 4.05P

R = 13.5%

We know, I = P × R × T/100

4.05P = P × 13.5 × T/100

4.05 = 13.5 × T/100

T = 4.05 × 100/13.5

= 405/13.5

= 30 years

Therefore, the number of years is 30 years.

**✦ Try This: **Bachhu Manjhi earns Rs.24000 in 8 months. At this rate, how many months does he earn Rs.42000?

**☛ Also Check: **NCERT Solutions for Class 7 Maths Chapter 8

**NCERT Exemplar Class 7 Maths Chapter 7 Problem 133**

## In how many years will the simple interest on a certain sum be 4.05 times the principal at 13.5 percent per annum

**Summary:**

The simple interest on a certain sum becomes 4.05 times the principal at 13.5 percent per annum in 30 years.

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