A sum of ₹ 600 put at 5% S.I. amounts to ₹ 720 in:

1. 3 years

2. 4 years

3. 5 years

4. 6 years

Manoj invested ₹ 8,000 for 10 years at 10% p.a. simple interest. The amount at the end of 2 years will be :

1. ₹ 9,600

2. ₹ 9,800

3. ₹ 16,000

4. None of these

A sum of money, lent out at simple interest, doubles itself in 8 years. Find:

(i) the rate of interest.

(ii) in how many years will the sum become triple (three times) of itself at the same rate percent?

Rupees 4,000 amounts to ₹ 5,000 in 8 years; in what time will ₹ 2,100 amount to ₹ 2,800 at the same rate?