Accuracy Question

2008-04-01 3:12 am
Please help with this question to do with accuracy!

The volume of a square pyramid is given by (b^2)h=3. If the base size b and the height h can be measured with an accuracy of 1%, how accurately can the volume be determined? State what assumptions you make.

回答 (1)

2008-04-04 3:09 am
✔ 最佳答案
Since volume V = (1/3)b^2.h

differentiate on both sides,
dV = (1/3)[b^2.dh + 2b.h.db]

dividing by V on both sides,
dV/V = (1/3)[b^2.dh + 2b.h.db]/V
i.e. dV/V = (1/3)[b^2.dh+ 2b.h.db]/[(1/3)(b^2.h]

dV/V = dh/h + 2(db/b)

since dh/h = db/b = 0.01 (i.e. 1%)
hence, dV/V = 0.01 + 2x0.01 = 0.03
or dV = 0.03V

therefore, the volume is of 3% uncertainty


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