santhosh_katkurwar wrote:Can someone explain with testing values approach. Also, what does it mean when questions in terms of something ? Here we need to find out in terms of m, y is what percent of x? I could write this y = ?/100 *x but i dint get it when it says in terms of x.
Here's a good general rule: if the question asks "what is p in terms of q?" that means that we want to ISOLATE p, and have it equal to some expression involving q:
p = ....q
(p equals something something q)
In this question, it's a bit more complicated, because the thing we want to isolate isn't clearly defined. Think of phrasing it this way: "what is (the percent that y is of x) in terms of m?" Let's define a new variable for (the percent that y is of x). Let's call it n. So here's what we want:
n = ...m
(n = something something m)
ALGEBRA:
If we want to do it algebraically, creating this new variable makes life a lot easier:
x is m percent of y ---> x = (m/100)y
y is what percent of x ---> y = (n/100)x
In order to get n in terms of m (but NOT in terms of x or y), we need to get rid of x and y. First, substitute what we have for x in the first equation into the 2nd:
y = (n/100)(m/100)y
y = (nm/10,000)y
Divide both sides by y:
1 = (nm/10,000)
Isolate n:
n = 10,000/m
So, we can get to answer
E.
However, nearly every time I see "in terms of" in a PS question, I think about whether plugging my own numbers in might be easier. In this case - when there are 3 variables given, 1 implied - it's definitely easier! I would do things slightly differently than Mitch did (though same idea).
PLUGGING IN NUMBERS:
I'd choose an x and a y that have an easy relationship, then see what m that gives us:
x = 2
y = 10
2 is 20% of 10, so m = 20
Now what percent is 10 of 2? It's 5 times as great, so 500%. n = 500. Since n is the thing we're solving for, our
target answer = 500, when we
plug in 20.
A. 100m ---> 100(20) = 500? Nope.
B. 1/100m ---> 1/(100*20) = 500? Nope!
C. 1/m ---> 1/20 = 500? Nope!
D. 10/m ---> 10/20 = 500? Nope!
E. 10000/m ---> 10,000/20 = 500? YES!
