Algebra help!!!

Ok, so I decided to go back to school after a looong layoff. Long enough that I have to take a placement test again. I picked up a packet of sample questions from the testing office and the english is no problem, but some of the math is giving me fits. (I used to be very good with math so this is really pissing me off)

Here’s the problem:
Sam and Mary each owned one-half stock in a printing company. Sam sold 2/3 of his stock to mary. What fractional part of the printing business does Mary now own?

I know that the answer is 7/10 because that’s what the answer key tells me… but WHY is the answer 7/10?

Sam sold 2/3 of 1/2 of the company stock to Mary. 2/3 * 1/2 = 1/3. So Mary now owns 1/2 + 1/3 of the company stock, or 5/6. Not 7/10–I’m not sure where they got that from.

I knew 7/10 sounded wrong. Damn it! of=x… 2/3 of 1/2 -> 2/3*1/2
I should’ve remembered that… that’s one of the basics!

Thanks ultrafilter.

No problem.

Is it possible that you misread the question? If the question stated that “Sam sold 2/5 of his stock to Mary,” then 7/10 would indeed be the answer. Or it might be that the person who wrote the question intended to write 2/5, but put down 2/3 by mistake.

No, I copied it directly off of the page.

A key thing to word problems is remembering words. Pick up any algebra textbook and you can find a glossary of terms. Off the top of my head

of= multiply
is = equal to
greater = add
less = minus


Those damn tests…I would believe the OP over the tester. The test was probably worded wrong, or the solution was a misprint.

You gotta love how the “test” is always right… I had to argue with a teacher over an answer because HE copied the question wrong out of the teacher’s edition to our textbook! He wouldn’t budge, so I had to appeal to the Department Head. Magically, the next day, the teacher just said he’s dropping that question without further explanation. (Putz!)

  • Jinx

Nah, the best was when I had to argue with my calculus teacher for 15 minutes about whether the average value of a function over an interval could be greater than the maximum value of the function on that interval. She was a useless twit anyway.

I’ve had a few of those confrontations, and it’s fascinating how a certain percentage of people - perhaps 10 - 15 percent - are utterly incapable of admitting error.