First half (Jan-Jun): Sum the balances for January through June, divide by 6.<br><br>
Second half (Jul-Dec): Sum the balances for July through December, divide by 6.<br><br>
Ratio = (Avg first half) : (Avg second half).<br>
Simplify the ratio by dividing both numbers by their HCF.<br><br>
Final Answer: Read from the graph and compute the simplified ratio.