Mathematics: It takes one examiner 15 hours to mark 80 exam papers. How long should it take 5 examiners to mark 80 exam papers

2.3Step-by-step explanation:....

It takes one examiner 15 hours to mark 80 exam papers.

Zaxx2974

20.01.2022

It will take 3 hours for 5 examiners to mark 80 papers.

Step-by-step explanation:

Given:

Time taken by an examiner to mark 80 exam papers = 15 hours

To find time taken by 5 examiners to mark 80 exam papers.

Solution:

Applying unitary method.

One examiner takes 15 hours to mark 80 exam papers

So, in one hour he can mark = $\frac{80}{15}$ papers

In hour 5 examiners can mark = $5\times \frac{80}{15}=\frac{80}{3}$ papers

So, we know 5 examiners can mark $\frac{80}{3}$ papers in 1 hours.

So, to mark 1 paper they will take = $1\div \frac{80}{3}$ = $\frac{3}{80}$ of a paper

Thus, to mark 80 papers they will take = $\frac{3}{80}\times 80 = 3$ hours.

Thus, it will take 3 hours for 5 examiners to mark 80 papers.

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