A solid metal frustum has bottom radius 9 cm, top radius 3 cm and height 12 cm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A solid metal frustum has bottom radius , top radius and height . It is melted and made into solid balls of radius . How many balls are made?
Need a reminder? The key ideaShow
A cone cut by a plane parallel to its base gives a small cone similar to the whole cone. If the small cone has the fraction of the height, it has of the curved surface and of the volume. One litre is . The volume of a melted solid is the same after it is recast.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The frustum. .
Step 2. One ball. .
Step 3. The number. .
Answer: balls.
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