Practice portal › Units and Measurements › Errors in Products, Quotients and Powers
Asked in JEE Main Online 2017 · Error in a power
Idea: every exponent weights its error in magnitude; the negative exponent on d still adds.
(Δ P)/P=1/2(Δ a)/a+2(Δ b)/b+3(Δ c)/c+4(Δ d)/d
=1/2(2%)+2(1%)+3(3%)+4(5%)
=1%+2%+9%+20%=32%.
The printed key gives 8%, which no reading of the exponents produces; the derivation stands. See DEFECTS.
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