M Zaid Arsad's answer to Raye's Primary 6 Maths Measurement Singapore question.
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May be incorrect. Not sure why the number given is not nice.
Date Posted:
5 years ago
This method, where the total volume of 4 cubes is added to the volume of the water, is correct only if all the 4 cubes are fully immersed in the water.
The answer of 7.319125 cm tells us that the water does not reach up to the top of the highest cube (at height of 9cm).
volume of water needed to fill up to 1st level of cubes
= 3 x (40 x 20 - 6 x 3)
= 2346
remaining volume of water
= 5747.3 - 2346
= 3401.3
remaining height of water
= 3401.3 / (40 x 20 - 3 x 3)
= 4.3
total height of water
= 3 + 4.3
= 7.3 cm
(Note that 7.3 = 3 + 3 + 1.3. This means that the water only reaches up to 1.3 cm on the 3rd cube)
The answer of 7.319125 cm tells us that the water does not reach up to the top of the highest cube (at height of 9cm).
volume of water needed to fill up to 1st level of cubes
= 3 x (40 x 20 - 6 x 3)
= 2346
remaining volume of water
= 5747.3 - 2346
= 3401.3
remaining height of water
= 3401.3 / (40 x 20 - 3 x 3)
= 4.3
total height of water
= 3 + 4.3
= 7.3 cm
(Note that 7.3 = 3 + 3 + 1.3. This means that the water only reaches up to 1.3 cm on the 3rd cube)
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