A can do a work in 15 days and B in 20 days. If they work on it together for 6 days, then what fraction of work is left?
Let total work to be done = 60 units
A's efficiency = $$\frac{60}{15} = 4$$ units/day
B's efficiency = $$\frac{60}{20} = 3$$ units/day
=> (A + B)'s 1 day's work = 4 + 3 = 7 units/day
Work done by A and B together in 6 days = $$6 \times 7 = 42$$ units
=> Work left = 60 - 42 = 18 units
$$\therefore$$ Fraction of work that is left = $$\frac{18}{60} = \frac{3}{10}$$
Create a FREE account and get:
Detailed syllabus & Topic-wise Weightage
By proceeding you agree to create your account
Free CAT Syllabus PDF will be sent to your email address soon !!!
