Bunuel
Three surgeons - Anna, Claire, and Diane - are asked to perform an emergency appendectomy. Working alone, Anna could complete the operation in 8 hours. Claire could do the job in 10 hours, while it would take Diane 12 hours by herself. On this particular shift, all three of the surgeons worked together on the appendectomy for two hours. At that point, Diane left to answer a page and never returned. An hour later, Claire left to handle another emergency - she also never returned. How long (in minutes) did it take Anna to complete the appendectomy, after
Claire and Diane both left?
A. 56
B. 60
C. 66
D. 70
E. 76
Given:
1. Three surgeons - Anna, Claire, and Diane - are asked to perform an emergency appendectomy.
2, Working alone, Anna could complete the operation in 8 hours. Claire could do the job in 10 hours, while it would take Diane 12 hours by herself.
3. On this particular shift, all three of the surgeons worked together on the appendectomy for two hours. At that point, Diane left to answer a page and never returned. An hour later, Claire left to handle another emergency - she also never returned.
Asked: How long (in minutes) did it take Anna to complete the appendectomy, after Claire and Diane both left?
Operation done in first 2 hours = 2/8 + 2/10 + 2/12 = (30+24+20)/120 = 74/120
Operation done in next 1 hour = 1/8 + 1/10 = 9/40 = 27/120
Operation left to be done by Anna = 1 - 74/120 - 27/120 = (120-74-27)/120 = 19/120
Time taken by Anna to complete the Operation = 19*8*60/120 minutes = 19*4 = 76 minutes
IMO E