A and B working separately can do a piece of work in 9 and 15 days respectively. If they work for a day alternately, with A beginning, then the work will be completed in:
A. 9 days
B. 10 days
C. 11 days
D. 12 days
Answer: Option C
Solution (By Examveda Team)
Work rate of A = $$\frac{{100}}{9}$$ = 11.11% work per day Work rate of B = $$\frac{{100}}{{15}}$$ = 6.66% work per day They together can do (A + B) = 11.11 + 6.66 ≈ 18% work per day They are working in alternate day, so we take 2 days = 1 unit of day Therefore, in one unit of day they can complete 18% of work (A + B) can complete 90% of work in 5 units of days. i.e. (5 × 18) And the rest 10% work will be completed by A in Next day So, total number of day, = 5 Unit of days + 1 day of A = 2 × 5 + 1 = 11 daysThis Question Belongs to Arithmetic Ability >> Time And Work
A=9
B= 15
Lcm
A=5
B=3
Alternatively A and B of total work 45
2*45/8=11.11 or 11
A's 1day work=1/9
B's 1day work=1/15
In 2days they can complete =(1/9+1/15)=8/45
8/45 part they can complete in=2 days
1 part they can complete in=2*45/8
=11.25 days
Or 11 days