​Rajneesh decided to invest in gold every month. He buys gold worth ₹65,000. He gets a rebate of 8% on it. After getting the rebate, he pays tax at the rate of 10%. Next month, he buys ₹70,000 with a rebate of 10% and tax 12%. What is the percentage change in his investment from the first month to the second month?

Correct option is C

​Given:

Month 1: Value = ₹65,000, Rebate = 8%, Tax = 10%

Month 2: Value = ₹70,000, Rebate = 10%, Tax = 12%

Formula:

​$$\text{Effective investment} = (\text{Value} - \text{Rebate}) \times (1 + \text{Tax rate})$$​​

$$\text{Percentage change} = \frac{\text{Investment in Month 2} - \text{Investment in Month 1}}{\text{Investment in Month 1}} \times 100$$​​

Solution:
Month 1:

​$$\text{Rebate} = 0.08 \times 65,000 = 5,200, \\ \ \\ \text{Taxable value} = 65,000 - 5,200 = 59,800$$​

​$$\text{Investment} = 59,800 \times 1.1 = ₹65,780$$​​

Month 2:

​$$\text{Rebate} = 0.1 \times 70,000 = 7,000, \\ \ \\ \text{Taxable value} = 70,000 - 7,000 = 63,000$$​

​$$\text{Investment} = 63,000 \times 1.12 = ₹70,560$$​​

Percentage Change:

​$$\frac{70,560 - 65,780}{65,780} \times 100 = 7.26\%$$​​

Thus the percentage increase is between 7 % to 8%