Question 36

A student multiplied a number by 5/7 instead of 7/5. What is the percentage error in the calculation?

Solution

Let the number be 'x'.

This number was supposed to be multiplied by '7/5' to get '7x/5'.

But it was multiplied by '5/7' to get '5x/7'.

So, percentage error = $$ \frac{\frac{7x}{5} - \frac{5x}{7}}{\frac{7x}{5}} * 100$$

= $$\frac{49-25}{49} * 100$$

= $$\frac{24}{49} *100 $$

$$\approx 48.98\%$$

=> Ans - (A)

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