Answer
The correct answer is B.
The approach to this type of question is to work in two steps:
(1) Finding the individual rate of work per printer
(2) Finding the additional number of printers needed
Step 1- The work rate of 6 printers together is one newspaper/ 12 hours => 1/12. Since each printer works at the same rate, we can say that each printer contributes 1/6th of the total work rate, meaning: (1/12)/6 = 1/72, or one printer/ 72 hours.
Step 2- We will insert what we have learned in Step 1 and the required time (hours) into the basic formula:
Work = rate*time.
1 newspaper = number of printers*(1/72) *8 hours
=> 1 = number of printers*1/9
=> Number of printers = 9
The number of printers includes the original six printers + the additional printers required. Thus, 9 - 6 = 3 additional printers.