Question 64

A student multiplied a number by 4/7 instead of 7/4. What is the percentage error in the calculation?

Solution

Let the number be 28

When the student multiplied it by 4/7, => original result = $$\frac{4}{7} \times 28 = 16$$

When the student multiply it by 7/4, => New result = $$\frac{7}{4} \times 28 = 49$$

=> Percentage error in calculation = $$\frac{(49 - 16)}{49} \times 100$$

= $$\frac{3300}{49} = 67.35\%$$

=> Ans - (B)

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