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

Redeem

Help With Work Problems

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 22
Joined: Wed Dec 30, 2009 1:59 pm
Thanked: 3 times

Help With Work Problems

by and1ms238 » Sat Feb 20, 2010 12:33 pm
I was reviewing the BTG Flash cards and I came across this flash card. Can someone help explain to me the concept of 'inverting' here?

In the example, is A the amount of time?

For example: If machine A makes 5 gallons per Hour and machine B makes 8 gallons per hour, then how many can the two machines make together in 1 hour?

How does the formula in the flash card relate? Thank you much in advance.
Image
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1022
Joined: Mon Jul 20, 2009 11:49 pm
Location: Gandhinagar
Thanked: 41 times
Followed by:2 members

by shashank.ism » Sat Feb 20, 2010 12:46 pm
and1ms238 wrote:I was reviewing the BTG Flash cards and I came across this flash card. Can someone help explain to me the concept of 'inverting' here?

In the example, is A the amount of time?

For example: If machine A makes 5 gallons per Hour and machine B makes 8 gallons per hour, then how many can the two machines make together in 1 hour?

How does the formula in the flash card relate? Thank you much in advance.
Image
see if a man do work in A hrs and other in B hrs say
so how much work he will do in 1 hr
a's work in 1 hr = 1/A
similarly B's work in 1 hr. = 1/B
total work in 1 hr = 1/A + 1/B

also if both can do work in T hr..
so their combined 1 hr work = 1/T

hence 1/A + 1/B =1/T/..
Hope it solves ur confusion....
My Websites:
www.mba.webmaggu.com - India's social Network for MBA Aspirants

www.deal.webmaggu.com -India's online discount, coupon, free stuff informer.

www.dictionary.webmaggu.com - A compact free online dictionary with images.

Nothing is Impossible, even Impossible says I'm possible.
Top
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Sat Feb 20, 2010 12:49 pm
and1ms238 wrote:I was reviewing the BTG Flash cards and I came across this flash card. Can someone help explain to me the concept of 'inverting' here?

In the example, is A the amount of time?

For example: If machine A makes 5 gallons per Hour and machine B makes 8 gallons per hour, then how many can the two machines make together in 1 hour?

How does the formula in the flash card relate? Thank you much in advance.
A is indeed the amount of time taken

In the example given , A makes 5 gallons per hour and B makes 8 gallons per hour; A&B together will make 13 gallons per hour.

If the question were A takes 2.6 Hours to make 13 gallons and B takes 1.625 Hours to make 13 gallons how much time will it take for A&B working together to make 13 gallons

In such scenario => 1/2.6+1/1.625 = 1/T

=> 1/1 = 1/T

T = 1 hour

I hope the concept is clear; A , B and T refer to time to get the specific amount of work done, not work done per time.
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
Post new topic Post Reply
• Page 1 of 1