two water pumps working simultaneously

[parakh.rahul]

rahul, think about the situation for a second: if both pumps are working together for 4 hours, then each pump works for the full 4 hours. i.e., your equation "sum of times = 4 hours" is incorrect; each individual time is 4 hours, as long as one of the pumps doesn't start or end before the other one.

Yes that makes complete sense. However, I would still like to know what the conclusion to this problem..

We cant add time of each pump because both are working simultaneously for 4 hours..its the work that is different for each machine..so we can only have two kinds of equations for this prob:

1) (P1 Work) + (P2 Work) = Total Work
2) (P1 Rate) + (P2 Rate) = Rate when working together

(P1 Time) + (P2 Time) = Total Time can only be used when one machine starts before the other and stops when the next machine starts.

I kinda understand the whole thing now..I just want a confirmation from your end. If I am still missing something please do let me know

Thanks so much

[RonPurewal]

rahul, i don't understand what you are trying to ask me. please write a question that's 1-2 lines long and fits in a single sentence -- in other words, "make it fit on a business card", as they say.
thanks.

[vivinkarkera]

I tried looking at this problem from a different prospective, I somehow managed to get the answer right but not sure whether my approach was right or was i just lucky?

can anyone please comment whether my approach was right?

Let's say the capacity of tank is 16 ltr.

Pipe A and Pipe B, both work together and fill 16 leters of water in 4hrs.

As per the question, One pipe is 1.5 faster than the other pipe.

Let pipe A = x and B = 1.5x

x+1.5x = 4

2.5x = 4

x = 1.6(Pipe A) and pipe B = 2.4

Now since the faster pipe is B and it has to fill 16lts

16/2.4

20/3

[RonPurewal]

I tried looking at this problem from a different prospective, I somehow managed to get the answer right but not sure whether my approach was right or was i just lucky?

can anyone please comment whether my approach was right?

Let's say the capacity of tank is 16 ltr.

Pipe A and Pipe B, both work together and fill 16 leters of water in 4hrs.

As per the question, One pipe is 1.5 faster than the other pipe.

Let pipe A = x and B = 1.5x

x+1.5x = 4

2.5x = 4

x = 1.6(Pipe A) and pipe B = 2.4

Now since the faster pipe is B and it has to fill 16lts

16/2.4

20/3

You've left some non-trivial steps unexplained. After looking at your solution for a while, though, I deduced that the green "4" is the result of the other green stuff.
Is that right?

If so, then your approach is flawless"”although I'm left a little confused by your question about "whether you were just lucky", considering that your solution is a perfectly methodical, step-by-step approach.
I.e., "just lucky" implies (to me) that you tried to guess some shortcut. I don't see anything in your approach that could be at all construed as a "shortcut" or "guess".

Which part is supposed to be the "lucky" part? Just curious more than anything else.

[vivinkarkera]

You've left some non-trivial steps unexplained. After looking at your solution for a while, though, I deduced that the green "4" is the result of the other green stuff.
Is that right?

Yes thats what i meant, sorry for the ambiguity

If so, then your approach is flawless"”although I'm left a little confused by your question about "whether you were just lucky", considering that your solution is a perfectly methodical, step-by-step approach.

Which part is supposed to be the "lucky" part? Just curious more than anything else.

i guess i wasn't confident enough with my approach and since it was bit different compared to the other's approach , i thought maybe i am doing something wrong.

thanks for the insight though!!

[RonPurewal]

i guess i wasn't confident enough with my approach and since it was bit different compared to the other's approach , i thought maybe i am doing something wrong.

^^ This is inaccurate, and is a rather limiting way to think about this exam.

Unless you are scoring in the bottom half of the quant scale, MOST quant problems can be solved in more than one way.

In fact, the primary purpose of your review"”later, when you are not operating under timed conditions"”should be to find as many DIFFERENT ways as possible to solve the problems.
This way, if you're taking the real test and your first approach to a problem gets "stuck", you'll have other things to try.

[RonPurewal]

thanks for the insight though!!

Sure.

[vivinkarkera]

^^ This is inaccurate, and is a rather limiting way to think about this exam.

Unless you are scoring in the bottom half of the quant scale, MOST quant problems can be solved in more than one way.

i guess this is why i am not able to cross 44 in Quant

In fact, the primary purpose of your review"”later, when you are not operating under timed conditions"”should be to find as many DIFFERENT ways as possible to solve the problems.
This way, if you're taking the real test and your first approach to a problem gets "stuck", you'll have other things to try.

As always there is lots to learn from your reply,will implement this in my future practice, thank a ton!!! :)

[RonPurewal]

i guess this is why i am not able to cross 44 in Quant

That's possible.

Remember"”Review of problems (later, without timing restrictions) has only 2 purposes:
1/ Identifying mistakes you made, and coming up with ways to prevent those mistakes in the future;
2/ Finding as many ways as possible to solve the problems.

If you are not addressing issue #2 here, then your review is of limited utility.

In particular, going back and reviewing the same methods you already used is essentially useless.
The whole point of review is to try other methods. You should spend MORE review time on methods you're LESS comfortable with.
The goal is to become comfortable with many different methods, so that you can switch seamlessly between methods if you get "stuck" with any particular attempt at a problem.

For some illustrations of problems solved in multiple ways, check out the videos titled "Flexibility in Problem Solving" here:
http://www.manhattangmat.com/thursdays-with-ron.cfm

[vivinkarkera]

Aah,
Thanks a ton Ron...really appreciate it, you guys are the best. :)

[RonPurewal]

Thanks for the kind words.