A bank offers 5% compound interest per half year. A customer deposits Rs. 6400 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest is:

The interest earned on 6400 from Jan to July will be $$6400 \times 5 \times \frac{1}{100}$$ (Since rate of interest is 5 % per 6 months)

= $$64 \times 5 = 320$$

Hence, 6400 will amount to 6720. He adds another 6400 to this. So the net amount becomes 6400 + 6720 = 13120.

Now interest earned on this amount in a period of 6 months will be $$13120 \times 5 \times \frac{1}{100} = 656$$

So the final amount will be 13120 + 656 = 13776

Total money he deposited = 6400 + 6400 = 12800

Hence, amount earned via interest = 13776 - 12800 = 976

=> Ans - (C)