Correct Answer - Option 3 : 20 yr

**Given**

A certain sum of money doubles itself in 10 yr. In how many years will it become 3 times at the same rate of simple interest

**Concept used**

Simple interest

**Calculation**

Let sum = Rs.x

Si = x

Time = 10 years

Rate = (interest × 100) / Principal × time

Rate = (100x) / 10x

Rate = 10%

Now sum = x, Si = 2x, Rate = 10%

Time = (interest × 100) / Principal × rate

Time = (2x × 100) / 10x

Time = 20 years.