Discussion of Question with ID = 088 under Percentages

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Question

A clerk multiplied a number by 2/1 instead of 1/2. What is the percentage of error?

A

75 %.

B

77 %.

C

73 %.

D

79 %.

Soln.
Ans: a

If the actual figure is x, the error is ${2x}/1$ - ${1x}/2$ = ${2^2x - 1^2x}/{2 × 1}$ = ${3x}/2$, so %-error = ${(3x)/2}/{(2x)/1}$ × 100 = ${3 × 1}/{2 × 2}$ × 100 = 75%.

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