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Expert: - 12/7/2008


Question
Hi Scott, I'm Rick and I'd like to resolve a math riddle that conventionally is very easy to solve, but in the "EXACT" way it's worded it becomes an aberration. In taking individual numbers apart in all ways, and then putting back the together in all ways  the result should always = the original sum . The following does not. A very bright teacher gave this riddle to me.

Take 3x10=30. We give the 30 to and individual. The individual decides to give back part of the 30. He takes five from the 30 then decides to only give back 3 and keep the ot 2. Common sense tells in giving back the 3 from the original sum of 30, the original sum of 30 now becomes 27, but how can this be when we consider the individual kept 2 and when added to the now sum 27, we can now only come up with a sum of 29, not the original sum of 30? Why is this so? Again I know how to get the original 30 in all ways except this one?
Thanks
Rick


Answer
3x10=30 is correct, so that's OK, and now the person has 30.

From the 30, he takes 5.
That means he has 5 in his hand and
there is 25 left in his pocket that he also has.

Of the five in his hand, he gave 3 of it away and kept 2.
He still has the 25 he kept in his pocket plus the 2 he kept in his hand, so he has a total of 27.  He gave 3 away.

It almost looks like the problem was the fact that he gave 3 away left him with 27 and then the 2 in his hand was thought about as well, but this 2 is part of the 27.  Is this it?

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Scott A Wilson

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I can answer any question in general math, arithetic, discret math, algebra, box problems, geometry, filling a tank with water, trigonometry, pre-calculus, linear algebra, complex mathematics, probability, statistics, and most of anything else that relates to math. I can even tell you it takes me over 2,000 steps to go a mile, but is that relevant?

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Experience in the area; I have tutored people in the above areas of mathematics for almost two years in AllExperts.com. I have tutored people here and there in mathematics since before I received a BS degree almost 25 years ago. In just two more years, I received an MS degree as well, but more on that later. I tutored at OSU in the math center for all six years I was there. Most students offering assistance were juniors, seniors, or graduate students. I was allowed to tutor as a freshman. I tutored at Mathnasium for well over a year. I worked at The Boeing Company for over 5 years. I received an MS degreee in Mathematics from Oregon State Univeristy. The classes I took were over 100 hours of upper division credits in mathematical courses such as calculus, statistics, probabilty, linear algrebra, powers, linear regression, matrices, and more. I graduated with honors in both my BS and MS degrees. Past/Present Clients: College Students at Oregon State University, various math people since college, over 7,500 people on the PC from the US and rest the world.

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My master's paper was published in the OSU journal. The subject of it was Numerical Analysis used in shock waves and rarefaction fans. It dealt with discontinuities that arose over time. They were solved using the Leap Frog method. That method was used and improvements of it were shown. The improvements were by Enquist-Osher, Godunov, and Lax-Wendroff.

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Master of Science at OSU with high honors in mathematics. Bachelor of Science at OSU with high honors in mathematical sciences. This degree involved mathematics, statistics, and computer science. I also took sophmore level physics and chemistry while I was attending college. On the side I took raquetball, but that's still not relevant.

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I earned high honors in both my BS degree and MS degree from Oregon State. I was in near the top in most of my classes. In several classes in mathematics, I was first. In a class of over 100 students, I was always one of the first ones to complete the test. I graduated with well over 50 credits in upper division mathematics.

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My clients have been students at OSU, people nearby, friends with math questions, and several people every day on the PC, and you're probably make one more.

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