Question

After 63 litres of petrol was poured into an empty storage tank, it was still 10% empty. How much petrol (in litres)must be poured into the storage tank in order to fill it?

• A. 6
• B. 7
• C. 9
• D. 8

Answer 1

Answer:

B. 7

To fill the storage tank completely, another 7 litres of petrol must be poured into it.

1. Find the current filled percentage:
   The tank is 10% empty, which means it is currently 90% full (100% - 10% = 90%).

2. Relate percentage to litres:
   The 63 litres of petrol that was poured into the tank represents this 90% capacity.
   $\text{90\% of total capacity} = 63\text{ litres}$

3. Calculate 1% capacity:
   $\text{1\% of total capacity} = \frac{63}{90} = 0.7\text{ litres}$

4. Calculate the amount needed to fill the remaining 10%:
   $\text{10\% empty space} = 10 \times 0.7 = \mathbf{7\text{ litres}}$