A water tank at a farm is being filled slowly by a garden hose overnight, ready for the next day's irrigation. After \(\frac{3}{5}\) of the tank's capacity ...
Question 1 Report
A water tank at a farm is being filled slowly by a garden hose overnight, ready for the next day's irrigation. After \(\frac{3}{5}\) of the tank's capacity has been filled, there are 480 litres still needed to fill the tank completely. Work out the total capacity of the tank. (3)
Answer Details
This question tests working backwards from a known remainder to find a total capacity. Since \(\frac{3}{5}\) of the tank has already been filled, the fraction still needed is \(1 - \frac{3}{5} = \frac{2}{5}\) [1 mark].
So \(\frac{2}{5}\) of the tank's capacity equals the 480 litres still needed [1 mark]. Dividing 480 by \(\frac{2}{5}\) (multiplying by its reciprocal, \(\frac{5}{2}\)) gives the total capacity: \(480 \div \frac{2}{5} = 480 \times \frac{5}{2} = 1200\) litres [1 mark].
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