29. If the error in calculating the radius of a wire is 1%, then the p

1.	29. If the error in calculating the radius of a wire is 1%, then the percentage error in its area is(a) 1%,(b) 2%(c) 3%.(d) 4%
Answer» area = πr² ∆area = π2r∆r∆area/area = π2r∆r/πr² = 2∆r/r but ∆r/r = 1% , so, ∆area/area = 2*(1%) = 2%

29. If the error in calculating the radius of a wire is 1%, then the percentage error in its area is(a) 1%,(b) 2%(c) 3%.(d) 4%

Answer»

area = πr²

∆area = π2r∆r∆area/area = π2r∆r/πr² = 2∆r/r

but ∆r/r = 1% ,

so, ∆area/area = 2*(1%) = 2%

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29. If the error in calculating the radius of a wire is 1%, then the percentage error in its area is(a) 1%,(b) 2%(c) 3%.(d) 4%

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