BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Rate of work

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 8
Joined: Tue Jun 14, 2011 2:35 pm

Rate of work

by khizarj » Tue Jun 14, 2011 2:38 pm
Machine A and B can finish a task in 6/5 of an hour. A and C and finish in 2/3 of an hour and B and C can finish in 2 hours. How long does it take for all three together to finish?

oops..posted in DS by mistake..how do i delete this?
Top
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 1309
Joined: Mon Apr 04, 2011 5:34 am
Location: India
Thanked: 310 times
Followed by:123 members
GMAT Score:750

by cans » Tue Jun 14, 2011 9:14 pm
a&b = 6/5 hours
a&c = 2/3 hours
b&c = 2 hours
(A&b)&(a&c)&(b&c) can finish in 1/ ( 1/(6/5) + (1/(2/3) + 1/2 ) = 1/ ( 5/6 + 3/2 + 1/2)) = 6/17
thus a&b&c can do in 3/17 hours
If my post helped you- let me know by pushing the thanks button ;)

Contact me about long distance tutoring!
[email protected]

Cans!!
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 135
Joined: Tue Mar 22, 2011 12:01 pm
Thanked: 21 times
Followed by:3 members
GMAT Score:720

by sourabh33 » Wed Jun 15, 2011 4:13 am
IMO 12/17

Let the total work be 30 units

1. A+B -> Time taken = 6/5 -> Rate of work = 30/6/5 = 25 units/hr
2. A+C -> Time taken = 2/3 -> Rate of work = 30/2/3 = 45 units/hr
3. B+C -> Time taken = 2 -> Rate of work = 30/2 = 15 units/hr

Adding rates of all three we get 2(A+B+C)= 85
Therefore Rate f a+b+c = 85/2

Now to find the time taken by a+b+c -> work/rate -> 30/85/2 -> 60/85 -> 12/17
Top
Post new topic Post Reply
• Page 1 of 1