Zorac (zorac) wrote,
Zorac
zorac

Number Puzzles

Somethin' to exercise your li'l (sorry) grey cells, a couple of numerical puzzles. First person to solve them both wins 15 seconds of fame.

If A and B can fill a tank in 4 hours, A and C can fill the tank in 5 hours, and B fills twice as fast as C, how long does it take for C to fill the tank alone?
Fairly straightforward, but either the Invariants being slow, or we were all being polite and letting other people have a chance to figure it out...

So, I'm broswing around Sainsbury's, when I see they have large packs of Strongbow (18x440ml cans, normaly £14.99) reduced to half price. Seems like a good offer, but they also have 4-packs at £3.59 each with 500 nectar points if you buy two packs. In addition, these cans have x% extra free, making them a full pint. Question is, which of these offers is better value for money?
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  • 10 comments
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Re: Easy, I think

ericklendl

October 24 2002, 14:33:51 UTC 18 years ago

Oh good. I'm very mistrustful of my own calculations, especially when mathematicians of jiggery_pokery's kaliber appear to query them. I used a 20 pint pot myself on my piece of rough paper, so I'm glad I was thinking in the right direction for once.

The minute error must therefore have been in the Strongbow/Frijj exchange rate. I guess I overlooked the implied assumption that having lots of Strongbow is considered "good" for the purpose of this question.

Re: Easy, I think

jiggery_pokery

October 24 2002, 16:02:08 UTC 18 years ago

'Twas a little gag. I thought you had got the correct answer, 20 hours, already, and had deliberately put "five plus fifteen minutes" instead of "five plus fifteen hours" just for jollity. Minute rather than minute, you see.

If I have to explain it...
<audience-shouts>...it wasn't funny!</audience-shouts>

Re: Easy, I think

ericklendl

October 24 2002, 16:19:19 UTC 18 years ago

Oops. That'll be -5 points for UK 'B' instead of the 25 it should have been... attention to detail is obviously a stronger suit for you than for me! If you could just mentally replace "0.25 minutes" with "0.00417 hours" in the previous comment, that would make it work properly. Sound good?

Re: Easy, I think

jiggery_pokery

October 24 2002, 17:12:10 UTC 18 years ago

You know, that's so much easier to read when they send you the version of it with HTML as raw text. The <b> tags stand out so easily. ;-)

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