A student erroneously multiplied a number by 2/5 instead of 5/2.What is the percentage error in the calculation?Choices:- 24% 54% 74% 84%

To find the percentage error, we first need to understand the mistake. The student multiplied by 2/5 when they should have multiplied by 5/2.

Let's assume the original number is x.

1. The student's result is (2/5)x.
2. The correct result should have been (5/2)x.

The error is the difference between the correct result and the student's result, which is (5/2)x - (2/5)x.

To find the percentage error, we divide the error by the correct result and multiply by 100%.

So, the percentage error is [((5/2)x - (2/5)x) / (5/2)x] * 100%.

Simplify the equation, we get [1 - (4/25)] * 100% = 84%.

So, the percentage error in the calculation is 84%.