Question

A student erroneously multiplied a number by 2/5 instead of 5/2.What is the percentage error in the calculation?​

Answer 1

Answer:

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Step-by-step explanation:

Let the number be 100. 2/5 of 100 is 40 while 5/2 of 100 is 250.

Now the difference is 210 on a base of 250. Therefore, percentage difference is 210/250 into 100 = 84%.

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Answer 2

Given,

A student erroneously multiplied a number by 2/5 instead of 5/2.

To find,

The percentage error in the calculation.

Solution,

We can simply solve this mathematical problem using the following process:

Let us assume that the student erroneously multiplied the number "x" by 2/5 instead of 5/2.

Now,

The correct calculation to be done by the student

= 5x/2

The incorrect calculation to be done by the student

= 2x/5

Error in the calculation

= The correct calculation to be done by the student - the incorrect calculation to be done by the student

= 5x/2 - 2x/5

= (25x - 4x)/10

= 21x/10

Now,

The percentage error in the calculation

= Error in the calculation/correct calculation x 100

= (21x/10)/(5x/2) x 100

= 21/25 x 100

= 84%

Hence, the percentage error in the calculation is equal to 84%.