A vendor sold 4 chocolates for ₹1, thereby gaining 100%. How many chocolates did he buy for ₹1?

Correct option is C

Given:

Selling rate: 4 chocolates for ₹1 

SP per chocolate = ₹1/4

Gain = 100%

Formula Used:

Gain % = $$\frac{\text{SP} - \text{CP}}{\text{CP}} \times 100$$​​

Solution:
Since gain is 100%, $$\text{SP} = 2 \times \text{CP}.$$​​
So, $$\text{CP} = \frac{\text{SP}}{2} = \frac{\frac14}{2} = \frac{1}{8}$$​ rupee per chocolate.
Hence, with ₹1, number of chocolates he could buy =$$\frac{1}{\frac18} = 8.$$​​