<p>I applied for as a pre-algebra tutor in a tutoring organization near my area, and I passed, but made some mistakes. One of which is this:</p>
<p>Judi went shopping with p dollars in her pocket. If the price of shirts was s shirts for d dollars, what is the maximum number of shirts Judi could buy with the money in her pocket?</p>
<p>(This asked for the formula to use to answer this question)</p>
<p>a. psd
b. ps/d
c. pd/s
d. ds/p</p>
<p>This may seem easy, but I'd like to see what you guys picked, and what you think of this problem.</p>
<p>You have p dollars. If X is the amount of ONE shirt, You can get p/X shirts.
X = d/s</p>
<p>p/(d/s) = ps/d</p>
<p>b. ps/d</p>
<p>Wow, thanks , alesteors… It’s been a long time since I’ve taken a math class- - I shouldn’t be tutoring now that I think about it.</p>
<p>There is another one I can’t understand:
Juan ate 1/3 of the jellybeans. Maria then ate 3/4 of the remaining jellybeans, which left 10 jellybeans. How many jellybeans were there to begin with?</p>
<p>I found the answer by process of elimination, and inputting a value in x.</p>
<p>But how would you solve this problem algebraically?</p>
<p>I got the same as Alesteors, but my reasoning was a little different:</p>
<p>This is a dimensional analysis problem.</p>
<p>The price is in shirts per dollars, and your money is in dollars.</p>
<p>You want an answer in shirts, so the dollars need to cancel, so p * s/d is dollars * shirts/dollars which cancels to ps/d shirts.</p>
<p>^^ I would reason like so: Maria ate 3/4, so the 10 left is 1/4. Thus the whole before Maria must have been 40. By the same reasoning, Juan ate 1/3, so 40 is 2/3, and the whole before Juan must have been 60.</p>
<p>In algebraic terms, 10 = 1/4(amount before Maria), and Amount before Maria = 2/3 (amount before Juan), which is X, so</p>
<p>10 = 1/4((2/3)X)</p>
<p>Solve for X</p>
<p>40 = (2/3)X
120/2 = X</p>
<p>X = 60</p>
<p>YonderMountain, thank you – I don’t remember solving these types of math problem – I don’t think it was part of the algebra topic (I’ve even taken a business calculus math!). </p>
<p>Thanks for pointing out that it’s a dimensional analysis problem. </p>
<p>I’ll go and check it out.</p>
<p>That’s how you got 60.</p>
<p>For some reason, I come up with:</p>
<p>x - 1/3x+[(x-1/3x0)]*3/4 = 10</p>
<p>LOL</p>
<p>It looks to me like you worked it forwards starting with X instead of backwards starting with the known 10 like I did.</p>