Question 67

A can do a work in 36 days and B in 12 days. If they work on it together for 3 days, then what fraction of work is left?

Solution

A & B total working unit is LCM of 36 & 12= 36 units.

A's working unit in a day=$$36\div36$$= 1 unit

B's working unit in a day=$$36\div12$$= 3 unit

Total work done by both in 3days= $$(1+3)\times3$$= 12 units.

Remaining work= (36-12)units= 24 units.

Fraction of work left= $$24\div36$$= $$2\div3$$

Therefore, Option A is correct.

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