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

Redeem

Simultaneous rates? easy help

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 322
Joined: Fri Mar 27, 2009 3:56 pm
Thanked: 24 times
GMAT Score:710

by mike22629 » Mon Apr 13, 2009 11:05 am
Use (1/a) + (1/b) = (1/t) formula

(1/20) + (1/30) = 5/60

60/5 = 12

Answer 12 minutes
Top
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Fri Apr 03, 2009 3:33 pm

by bronzie35 » Mon Apr 13, 2009 11:32 am
How do you copy the practice test problem and attach it here? I've tried over and over to copy but I can not figure out how to do it.

Thanks.
Top
Master | Next Rank: 500 Posts
Posts: 392
Joined: Thu Jan 15, 2009 12:52 pm
Location: New Jersey
Thanked: 76 times

by truplayer256 » Mon Apr 13, 2009 12:26 pm
Aside from Mike22629's formula to solve this problem, this problem can also be solved by doing the following:

Let the depth of the pool equal x.

The smaller hose can fill the pool at x/30 per min and the bigger hose can fill the pool at x/20 per min. From this, we can conclude that both hoses can fill the pool at x/30+x/20= x/12 per min simultaneously. Now, we need to know how many minutes it'll take the fill the pool, which is of depth x. Since both hoses fill the pool at x/12 per min, we can do (x)/(x/12) to find out how many mins it'll take them to fill the whole pool. The answer comes out to be 12.
Top
Post new topic Post Reply
• Page 1 of 1