Question

Four examiners evaluate certain number of papersin 8 days working 5 hours a day.if 2 examiners evaluate twice the number of papers in 20 days,then how many hours per day should thet work?

Answer 1

Find the number of papers a single examiner can evaluate in a day:

Let the number of papers evaluated by the 4 examiners be x

Step 1: The four examiners evaluate the following fraction each day(8 day):

x/8

Step 2: The fraction they evaluate in an hour ( they work 5 hours a day)

x/8 ÷ 4   = x/8 × 5 = x/40

Step 3: Each examiner evaluates the following fraction in 1 hour:

x/40 ÷ 4  = x/40 × 1/4 = x/160

Therefore x/160 of the total papers is what each examiner can examine in 1 hour.

If 2 examiners evaluate twice the number of papers in 20 days,then how many hours per day should they work?

To answer this we will need to work backwards:

Twice the work  = 2 × x = 2x

Working 20 days that means they will evaluate:

2x/20 in 1 day = x/10 of the papers

If 1 examiner  = x/160 in hour,
Then 2 examiners = x/160 × 2 = x/80

The 2 examiners can evaluate x/80 of the papers in 1 hour

Therefore if x/80 is 1 hour, how long will x/10 take:

If x/80  = 1 hour
Then x/10 = 1 hour × x/10 ÷ x/80

 = 1 × x/10 ×80/x = 80/10 hours = 8hours

Therefore the examiners will have to work 8 hours per day

Answer 2

Answer:

8 hours

Step-by-step explanation:

by using this formula,(m1*d1*h1)/w1=(m2*d2*h2)/w2

by subsitute the given values,we get

m=men,d=days,h=hours,w=work

(4*8*5)/1=(2*20*h)/2*1

because twice the work

sol eq we get 8 hrs as ans