Challenging Qn for Brain

[Gary84]

answer??

[Sturtles]

Just a brain teaser Qn for you:

 

2 pipes takes 5 minutes to fill up a tank, and the smaller pipe alone takes 6 minutes more than the bigger pipe to fill the tank. How long would it takes for the bigger pipe to fill the tank alone?

 

I will provide the answer shortly.

 

Is it 8.653minutes?

 

This question seems to also test the rationality of the students.

 

Should be O-levels type of questions

[Relagsingh]

5 mins?

[Wolverman]

Just a brain teaser Qn for you:

 

2 pipes takes 5 minutes to fill up a tank, and the smaller pipe alone takes 6 minutes more than the bigger pipe to fill the tank. How long would it takes for the bigger pipe to fill the tank alone?

 

I will provide the answer shortly.

 

 

Correct your grammar dude

[Enotsol]

The exact answer was given by Xtraun but seeing that this is supposed to be a brain teaser and not a number crunching game... I wonder if there's some catch to it..

[Jman888]

elementary math means E maths in A level or PSLE maths?

 

I think someone who dunno this would still be able to get through degree in accountancy in my times..

 

accounting is creative maths, has nothing to do with real maths

[Cavver]

2.5 min ???

[Yc86]

here's my attempt:

 

s = small pipe

b = big pipe

 

s + 6min = b ---- 1

 

b + s = 5min

s = 5min - b ------- 2

 

sub 2 into 1

 

5min - b + 6min = b

b = 5.5mins

 

am i correct?

[Kingkong]

5( x/(y+6) + x/(y)) = x

5y + 5y + 30 = y^2 + 6y

y^2 - 4y - 30 = 0

y = (4 + 11.66)/ 2 = 7.83

 

I just couldn't get the last line out...

But that should be the answer.

[Chevypower]

my guess is 9mins.

 

9 + 6 = 15 9/15 x 5 = 3 6/15 x 5 = 2

 

3+2 = 5.

 

hehehe... wild wild guess.....

 

:)

Edited September 22, 2007 by Chevypower

[Leslielai]

You smell like a thoroughly incompetent tutor to me.

 

It is not the first time you are posting mathematical questions in this forum and each time you expect people to come up with complete answers for you.

 

So, are you one?

Edited September 22, 2007 by Leslielai

[Guyver]

Just a brain teaser Qn for you:

 

2 pipes takes 5 minutes to fill up a tank, and the smaller pipe alone takes 6 minutes more than the bigger pipe to fill the tank. How long would it takes for the bigger pipe to fill the tank alone?

 

I will provide the answer shortly.

 

Wah chim ...

Edited September 22, 2007 by Guyver

[Sfhuang]

Let the time for the bigger pipe to fill the tank alone be x minutes. (0

 

That means it would take the smaller pipe 6+x minutes to fill up the tank.

 

Put the small pipe into one tank and the bigger pipe into another similar tank, in 6+x minutes you would have 1 filled tank (from the small pipe) and (6+x)/x full tank (from the big pipe).

 

Now that means that both pipes put together would fill 6/x+ 1 + 1 tanks in 6+x minutes.

 

From the fact that the 2 pipes put together takes 5 minutes to fill up 1 tank, we then have by virtue of direct proportion:

 

[6/x+2]/1=[6+x]/5

30+10x=6x+x^2

x^2-4x-30=0

Solving the quadratic equation:

We get x=7.83 or x=-3.83(rejected)

 

So my answer is it takes the bigger pipe 7.83 minutes to fill the tank alone. [QED]

[Sfhuang]

Steady same answer.

[Chembeng]

5( x/(y+6) + x/(y)) = x

5y + 5y + 30 = y^2 + 6y

y^2 - 4y - 30 = 0

y = (4 + 11.66)/ 2 = 7.83

 

Quite a creative way to introduce 2 variables with different units - x is tank volume, y is L.P. rate.

 

You could simply do without x. Do 'rate' balance, and u can skip first line.

 

Good still.

[Mummypenguin]

Just a brain teaser Qn for you:

 

2 pipes takes 5 minutes to fill up a tank, and the smaller pipe alone takes 6 minutes more than the bigger pipe to fill the tank. How long would it takes for the bigger pipe to fill the tank alone?

 

I will provide the answer shortly.

 

I've a feeling that this is a Pri school question that you need to use model to solve.

 

My try:

 

Time taken for big pipe to fill tank = B

Time taken for small pipe to fill tank = B+6

Time taken for fill 2 tanks using both pipes = B+B+6 = 2*5min

So 2B + 6 = 10

B = 2

correct?

 

Trying very hard to follow my P2's math text, hoping that next time I'll be able to teach her using the model's method i.s.o algebra.

 

Are you a parent trying to teach your kid or are you really a tutor that can't solve your students' questions?

Because I've also notice that you usually ask for solutions to math questions.

[Poper]

Hhmmm... the TS has not made any response since day 1...

[Poortraveller]

assuming the flow rate is the same ... bigger pipe will fill up the tank faster, my guess should be <6min