Five full-time employees and 6 interns work 12 hours a day and finish a task in 20 days. 8 full-time employees and 18 interns work 10 hours a day and finish the same task in 12 days. How many are working hours per day required if 5 full-time employees and 6 interns work for 30 days to finish the same amount of work? We may assume that changing number of people in a group does not change productivity.
(A) 8 hours a day
(B) 7 hours a day
(C) 6 hours a day
(D) 5 hours a day
Answer: (A)
Explanation: (5 full time + 6 interns) * 12 * 20 = (8 full time + 18 interns) * 10 * 12
(5 full time + 6 interns) * 2 = (8 full time + 18 interns)
2 full time = 6 interns
1 full time = 3 interns.
Now (8 full time + 18 interns) * 10 * 12 = (5 full time + 6 interns) * x * 30
42 interns * 12 * 10 = 21 interns * x * 30
X = 8 hours a day.
