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15 rubies lay in the sand. If you divide them by a third and add 15 more, how can you make 3 equal piles?

Divide 15 rubies by three -- gives you three piles of 5.

Add 15 more, divided by three piles -- gives you three piles of 10.

Thus, make three piles of ten. The "twenty" answer is wrong because it requires adding 45 more, not 15.

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Divide 15 rubies by three -- gives you three piles of 5.

Add 15 more, divided by three piles -- gives you three piles of 10.

Thus, make three piles of ten. The "twenty" answer is wrong because it requires adding 45 more, not 15.

Sorry, this is incorrect. The previous answers are correct. You are dividing by 3, when the OP asks to divide by 1/3.

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Well Im sorry folks but the correct answer is 3 piles of 6 rubies and how that is obtained as the correct answer is this divide the 15 rubies by a third now if you divide 15 by a third then you will divide 15 by 5 which is 3 then add 15 more hence the total is now 18 viola the answer.

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I actually believe that multiple answers exist depending on your interpretation. Does "divide by a third" mean mathematically, or the actual third of 15? And it does say you only add 15 more rubies, so the division step (mathematically taken) can be considered 'theoretical', versus the actual 15+15. Congrats to those who thought outside the box of a basic math problem

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This is one reason I am so against our current state of the government... They can't even manage to supply a sufficient education system to teach people basic math... Very disheartening...

.............whats his problem?

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I actually believe that multiple answers exist depending on your interpretation. Does "divide by a third" mean mathematically, or the actual third of 15? And it does say you only add 15 more rubies, so the division step (mathematically taken) can be considered 'theoretical', versus the actual 15+15. Congrats to those who thought outside the box of a basic math problem

Hmmm... interpreting math... that's ah... interesting...

Divide x by a third means: x/(1/3) or x/.3333 (rounding to the nearest ten thousandth). Not: x/(x/3). That would be written as: divide x by a third of x. "a" in math is taken to mean "one", not "a ___ of ___" nor "a completely random value decided by the participant."

It's a good attempt... but ah... I'm not quite sure how "interpretable" math is when not dealing with variables, such as "we interpret n as some number in the series N".

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.............whats his problem?

The fact that this is probably the easiest problem on the board, and people want to debate a math problem!?

Hmmm... interpreting math... that's ah... interesting...

Divide x by a third means: x/(1/3) or x/.3333 (rounding to the nearest ten thousandth). Not: x/(x/3). That would be written as: divide x by a third of x. "a" in math is taken to mean "one", not "a ___ of ___" nor "a completely random value decided by the participant."

It's a good attempt... but ah... I'm not quite sure how "interpretable" math is when not dealing with variables, such as "we interpret n as some number in the series N".

+1..... no better yet +895,089!!! I like your sarcastic cynicism while dealing with topics most people can't comprehend! funny...lol...interpret math! HA

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While I realize that technically "divide by a third" means to multiply by three, I don't see how this makes sense in a non-abstract setting. It's one thing to say "divide fifteen by a third", and yet it's another thing to say, "I decided to divide all of my wife's jewelry by a third." Anyone who understands math can do the former, but anyone who can do the latter needs to explain to me how one goes about such a procedure, because it would be quite useful come Christmas, or any day for that matter.

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While I realize that technically "divide by a third" means to multiply by three, I don't see how this makes sense in a non-abstract setting. It's one thing to say "divide fifteen by a third", and yet it's another thing to say, "I decided to divide all of my wife's jewelry by a third." Anyone who understands math can do the former, but anyone who can do the latter needs to explain to me how one goes about such a procedure, because it would be quite useful come Christmas, or any day for that matter.

It can be done easily but not cheaply. Happy jewelry shopping. :)

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Alot of people are not understanding this when it is actually very simple maths.

The big thing that must be remembered here is when you divide by a fraction it is the same as multiplying by the reciprocal. e.g. If you did 10/ 1/2 it is the same as doing 10*2

so in this case there is 15 rubies in the sand

The first step is to divide this by 1/3 not 3 of a 3rd of 15. Quite simply 15 divided by 1/3

So when showing the full working out it goes like this

15 / 1/3 (then as you know 15=15/1) = 15/1 / 1/3 = 15/1 * 3/1 (then the bottoms are irrvelevent as 15/1 = 15 or 1*1=1 so it means nothing)

So as you can see I am doing 15 times by the reciprocal of 1/3 = 3/1 = 3 so...

15*3 = 45

The next step is obvious. You are wanted to add 15 more rubies to this so...

45+15=60 rubies

Now you want 3 piles so now you divide 60 by 3 so...

60/3 = 20 so 20 rubies in each pile!

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ummm.... if there are only 15 rubies in the sand.... how can their be 3 groups of 20?... I'm confused now. :huh:

Well if you divide it by third you actually have to multiply that number with 3 ... so it's 15*3=45+15=60 and then you get 3 piles of 20.

I'm not really familiar with the math terminology in English. :blink:

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has anyone else noticed that the original poster has already given an affirmation to the first answer? It's seriously like the third post, how there has been this much discussion of a problem that's been answered is really a mystery to me.

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Divide 15 rubies by three -- gives you three piles of 5.

Add 15 more, divided by three piles -- gives you three piles of 10.

Thus, make three piles of ten. The "twenty" answer is wrong because it requires adding 45 more, not 15.

well i wasnt much good at math in school, but it sure seems to me that dividing 15 by 1/3, means dividing by 3... thats 5 in each pile, add 15 more thats five more is a total of 30. 15 +15 was 30 in my school. so again you divide 15 by 3 is still 5, thus 3 piles of 10. the only way i know of to get any other answer is to add a black hole or something.

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