Quickie maths question

[WOM]

Help Mrs WOM win a thermos at her staff meeting:

If pipe A fills a pool in 2 hours, and pipe B fills a pool in 4 hours, and pipe C fills a pool in 8 hours, how long will it take to fill a pool if all three pipes are filling it at the same time?

Cheers.

[Wyatt Earp]

Quickie maths question

1 1/7 hours.

[WOM]

Quickie maths question

I worked it out to 1 hour, 7 minutes, 30 seconds. Is that the same? Sorry...my brain has morning weakness.

[Gangster Octopus]

Quickie maths question

WE, show us your equation.

[Wyatt Earp]

Quickie maths question

No, not the same: what's your working?

Mine was that in one hour, the first pipe contributes half a pool, the second 1/4 and the third 1/8, making 7/8 of a pool in total per hour. So for one whole pool, we need 1/(7/8) = 8/7 hours: one and a seventh.

[WOM]

Quickie maths question

I can't work with fractions. Bad grounding.
Mine was:
A fills at .5 a pool an hour
B fills at .25 a pool an hour
C fills at .125 a pool an hour

One hour is .875 a pool, with .125 remaining to be filled, which is 7 minutes, 30 seconds (.125 of an hour).

[Donnchadh Ghairdinéir]

Quickie maths question

Say the amount of water in the pool is x litres. So in one hour, hose A fills x/2, hose B x/4 and hose C x/8. Added together, 7x/8. So to fill the pool you need 7x/8 * 8 hours/7, or about 68.5 minutes.

Edit- WOM is multiplying 7/8 by 9/8, not 8/7.

[Wyatt Earp]

Quickie maths question

WOM: not .125 of an hour, .125 of a pool.

[Wyatt Earp]

Quickie maths question

Budgie Smuggler wrote:

Say the amount of water in the pool is x litres. So in one hour, hose A fills x/2, hose B x/4 and hose C x/8. Added together, 7x/8. So to fill the pool you need 7x/8 * 8 hours/7, or about 68.5 minutes.

Edit- WOM is multiplying 7/8 by 9/8, not 8/7.

Right answer, but I don't get the 7x/8*8 hours/7 bit.

[WOM]

Quickie maths question

Nuts.

Okay, so represented as minutes, is Budgie right with 1 hour, 8 minutes and 30 seconds? Or is 1 1/7 hours more accurate?

And thanks all.

[Wyatt Earp]

Quickie maths question

1 1/7 hours is exactly accurate: Budgie's is an approximation.

[Wyatt Earp]

Quickie maths question

Budgie's approximation is correct to the nearest ten seconds.

[WOM]

Quickie maths question

Lovely. Thanks very much.

[Wyatt Earp]

Quickie maths question

1 hr, 8 minutes, 34.285714 secs, to be absurdly accurate.

[Donnchadh Ghairdinéir]

Quickie maths question

Right answer, but I don't get the 7x/8*8 hours/7 bit

7/8 [full-pool-litres, effectively] times 8/7 [hours] equals 1 full pool.

Isn't our working the same?

[Wyatt Earp]

Quickie maths question

Yeah, sorry, I knew it had to be, I just wasn't following.

[JtS]

Quickie maths question

Isn't it cheating to give Mrs WOM the answer rather than helping her work it out?

[Wyatt Earp]

Quickie maths question

It's only a bleedin quiz, it's not as if she's doing her GCSEs.

[JtS]

Quickie maths question

So it's not what you know it's who you know.

[Wyatt Earp]

Quickie maths question

And what who you know know.

[WOM]

Quickie maths question

And Mrs WOM is the proud owner of a new lunch-sized, keeps-your-soup-hot type thermos thingy. May or may not be an actual Thermos (TM) brand product. Apparently she's the toast of the lunchroom.

Cheers all.

[Wyatt Earp]

Quickie maths question

Is JtS' ethical question bugging you, at all? There may be a more deserving candidate whose tea is getting cold even as we speak.

[WOM]

Quickie maths question

Their tea is none of my concern.

No, she was charged with providing a correct answer. And she did so.

She also suspects that she might have been the only one to submit an answer, as many of her fellow teachers are jaded old crustbuckets for whom the allure of a free thermos has long since been replaced by their well-funded retirement coming into view.

I shall sleep soundly tonight. But largely due to my new feather pillow from President's Choice ($9.95).

[JtS]

Quickie maths question

But does she now know how to solve the problem? If she does then it's good work all round, if she doesn't I feel it's a somewhat hollow victory

[Mumpo]

Quickie maths question

Who sets a fucking maths quiz to win something as trivial a Thermos anyway? What's wrong with a fucking raffle?