To cut down on their water bill, the Ibrahim family fitted a water butt in the garden that collects rainwater from the roof for use outdoors. It stands 120 ...
Question 1 Report
To cut down on their water bill, the Ibrahim family fitted a water butt in the garden that collects rainwater from the roof for use outdoors. It stands 120 cm high, and the diagram below shows how full it currently is, with the water level measured from the bottom.
- Work out the height of water in the butt as a percentage of its full height. (3)
Answer Details
Expressing one measurement as a percentage of another uses \(\frac{\text{part}}{\text{whole}} \times 100\), here comparing the height of water in the butt with its full height.
(a) Water height as a percentage of the full height:
\[ \frac{78}{120} \times 100 = 65\% \][3]
The water butt is treated as having a uniform cross-section from top to bottom, which is why the height reading alone is enough to give the percentage full; without that assumption, height and volume would not be proportional.
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