Question

If 4 examiners can examine a certain number of
answer books in 8 days by working 5 hours a day,
for how many hours a day would 2 examiners have
to work in order to examine twice the number of
answer books in 20 days.​

Answer 1

Answer:

8hrs

Step-by-step explanation:

M1*D1*H1 M2*D2*H2

_______ = _________

W1 W2

M men, D days, H hours per day,W is the work

M1=4, D1=8, H1=5, W1=w

M2=2, D2=20,H2=h, W2=2w

substitute in above equation

4×8×5/w =2×20×h/2w

h=4×8×5×2w / 2×20× w = 8w / w =8hrs

Answer 2

Given are the number of days and hours examiners take to examine papers, Find the number of hours to examine twice the number of papers

Explanation:

• Let the number of examiners be denoted by 'n'.
• Let the number of days these examiners take to examine the papers be denoted by 'd'.
• Let the number of hours each of them works in a day be denoted by 'h'.
• Let the total amount of work done to examine a certain amount of papers be denoted by 'W'.
• Then we have,   $->W=ndh$
• Hence in the first case we have,  $n=4,\ d=8,\ h=5$
•                           $->W_1=4(8)(5)\\->W_1=160$  
• Now in the second case we have, $n=2,\ d=20,\ W_2=2W_1,\ h=?$  
•                           $->2W_2=2(20)(h)\\->2(160)=40h\\->h=8\ hrs$  
• The examiners should work for $8\ hrs/day$ to examine twice the number of answers.