Answer:
$97,958.42
Step-by-step explanation:
To solve this problem we can use the compound interest formula which is shown below:

<em>P = initial balance
</em>
<em>r = interest rate
</em>
<em>t = time
</em>
<em>
</em>
First change 6.5% to its decimal form:
6.5% ->
-> 0.065
Next plug in the values:


They have to pay back $97,958.42
2 litres every 2.5 minutes is 4 litres every 5 minutes so therefore, it is 0.8 litres/minute (800ml per minutes)