Lesson: Assigning Variables

Comment on Assigning Variables

Hi Brent, Your explanations are awsome!
i would like to ask you :
How are we (non americans are supposed to deal with the nickel / quarter thing (Talking about the first ressource above) is there any trick i could learn so i can deal with this issue ?
Ben
gmat-admin's picture

Great question, Ben!
The first linked question in the Related Resources box is not an official GMAT question. I seriously doubt that an official question would require test-takers to know the value of dimes, nickels, etc. Instead, they will just say $0.10, $0.05, etc

BTW, I'm not American either :-)

Thank you !
This would be a real struggle for intational students. I just walked through the OG, not a single one looks like that.
Thank you again, your videos are the best ressources i've seen so far !
Have a good day

Brent this might seem dumb or maybe I just am tired today but why is your 'twice as many cats as dogs': 2D = 1C?

Shouldn't it be 2C = 1D? For every 2 cats there's one dog?
gmat-admin's picture

You're not alone; many students mistakenly believe that "twice as many cats as dogs" translates into 2C = 1D.

If there are twice as many cats as dogs, then we can say that (the number of cats) ≠ (the number of dogs)

Our goal is to create an equation that we can solve. So, how do we make the above quantities equal?

Do we take the larger quantity (the number of cats) and make it even bigger my multiplying that quantity by 2? Definitely not.

Instead, we take the smaller value (the number of dog) and multiply it by 2 to get: C = 2D.

We can also try this with some specific values.

If there are "twice as many cats as dogs," then it's possible that there are 10 cats and 5 dogs. At this point, it's clear that (the number of cats) ≠ (the number of dogs), because when we replace the bracketed parts with 10 and 5, we get: 10 ≠ 5

How do we make the two quantities equal? We take the smaller quantity, 5 (which represents the number of dogs) and multiply it by 2 to get: 10 = (2)(5)

So, we can also write: (the number of cats) = 2(the number of dogs)

Hi Brent, In the 3rd Reinforcement question (the question on ropes), would the answer be D if we were to mention in the question that all the ropes have integer lengths? Thanks!
gmat-admin's picture

Question link: https://gmatclub.com/forum/a-length-of-rope-is-cut-into-three-different-...

That's right, Bullzi. If the 3 ropes had to have integer lengths, then the correct answer would be D

Hi, Brent! This might be a silly question. But I had trouble with this several times.
Here,
N=2009 population;
1.1N=2010 population.

Why not
N+10%
=N+10/100
=N+1/10
gmat-admin's picture

Your calculations are very close to mine, except you missed something.

If we want to algebraically represent a number that's 10% greater than N, then we can go about it in two ways:

#1) 1.1N

#2 N + (10% of N) = N + 0.1N
= 1N + 0.1N
= 1.1N

Does that help?

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