Two typists undertake to do a job. The second typist begins working one hour after the first. Three hours after the first typist has begun working, there is still 9/20 of the work to be done. When the assignment is completed, it turns out that each typist has done half the work. How many hours would it take each one to do the whole job individually?
- 5 hr and 4 hr
- 12 hr and 8 hr
- 8 hr and 5.6 hr
- 10 hr and 8 hr
Let the first typist takes X hours and the second Y hours to do the whole job.
When the first was busy typing for 3 hr, the second was busy only for 2 hr. Both of them did 11/20 of the whole work.
3/X + 2/Y = 11/20
When the assignment was completed, it turned out that each typist had done half the work. Hence, the first spent X/hr, and the second, Y/2 hr.
And since the first had begun one hour before the second,
X/2 - Y/2 = 1
X = 10 hr, Y = 8 hr
The correct option is D.