Arvind deposited a sum of money with a bank on 1^st january, 2012 at 8% simple interest per annum. He received an amount 3144 on 7^th August, 2012. The money he deposited with the bank was = ?
a) Rs. 3080
b) Rs. 2500
c) Rs. 3000
d) Rs. 3100

Answer: c
Explanation:
$$\eqalign{ & {\text{Amount = Rs}}{\text{. 3144}} \cr & {\text{Rate = 8}}\% \cr & {\text{Let, Principal = Rs}}{\text{. }}x \cr & {\text{Time = }} \cr & \frac{{30 + 29 + 31 + 30 + 31 + 30 + 31 + 7}}{{366}} \cr & = \frac{{219}}{{366}} \cr & {\text{SI = }}\frac{{{\text{P}} \times {\text{R}} \times {\text{T}}}}{{100}} \cr & \Rightarrow 3144 – x = \frac{{x \times 8 \times 219}}{{100 \times 366}} \cr & = {\text{Rs}}{\text{. 3000}} \cr} $$