Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A village in Kenya stores water in a spherical tank. A surveyor measures its radius as , with a possible error of . Find the volume from the measured radius. Then use a differential to estimate the error in the volume, and the percentage error in the volume.
and . The relative error is , the percentage error is , and for the relative error in is times that in .
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 volume. .
Step 2. The error. .
Step 3. The percentage error. , so the percentage error is .
Check. The rule gives the same number.
Answer: , an error of about , which is .
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