A student multiplied a number by 3/5 instead of 5/3, What is the percentage error in the calculation ?
Correct Answer: Option B
Let the number be x.
Then, ideally he should have multiplied by x by 5 \(\div\) 3. Hence Correct result was x \(\times\) (5 \(\div\) 3)= 5x \(\div\) 3.
By mistake he multiplied x by 3/5 . Hence the result with error = 3x \(\div\) 5
Then, error = (5x \(\div\) 3 - 3x \(\div\) 5) = 16x \(\div\) 15
Error % = (error \(\div\) True vaue) \(\times\) 100 = [(16 \(\div\) 15) \(\times\) x \(\div\) (5 \(\div\) 3) \(\times\) x] \(\times\) 100 = 64 %
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