P6 Work backwards from volume or area
Cuboid height — volume 480 cm³
A cuboid has volume 480 cm³, length 15 cm and width 8 cm. Find its height.
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4 cm
The pattern behind it: Work backwards from volume or area
Use the known area or volume to find the missing measurement.
In this one. Volume is the area of one layer multiplied by the height. Divide by the base area to find the missing height.
How to spot it
The question gives a cuboid's volume with two dimensions and asks for the third, or gives the volume with one length and asks for a face area. A square's area given with its side asked for belongs here too.
Common mistake
Children divide the volume by a length lying inside the face they want, instead of the length that runs into it, and get the wrong kind of measurement.
Try one like it
Standard A square with area 100 cm² A square has area 100 cm². Write its side length using square-root notation, then evaluate it.The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.