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- General GMAT Strategies - 7 videos (all free)
- Data Sufficiency - 16 videos (all free)
- Arithmetic - 38 videos (some free)
- Powers and Roots - 36 videos (some free)
- Algebra and Equation Solving - 73 videos (some free)
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- Analytical Writing Assessment - 5 videos (all free)
- Reading Comprehension - 10 videos (all free)
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- Integrated Reasoning - 17 videos (some free)

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## Comment on

c percent of c## Since ab/100=c, if we plug in

Could you please check?

## How did you conclude that b =

How did you conclude that b = 10?

## Hi,

Apologies. I made a silly mistake. Anyway, I really like all your videos. They are amazing.

Thank you so much.

## Glad you like them!

Glad you like them!

## Hi,

Is it necessary that the solution should have only numerical value or can there be variables as well?

## Great question.

Great question.

If a Data Sufficiency question asks us to determine the value of some variable, we must be able to provide a single numerical value in order to conclude that the statement is sufficient.

Here's an example:

What is the value of x?

(1) 5x = 2k

If we try to solve for x, we get x = 2k/5. Since we can't provide an actual numerical value for x, statement 1 is not sufficient.

## Can we write question stem

C=0.01ab and we need to find 0.01c^2 -?

from statement 1:

ab=2500/c replace in question stem c=0.01 * 2500/c and hence c^2=25 ; from here we can replace 0.01C^2= 0.01*25=0.25 - Suff

from statement 2:

a=b/c replace in question stem c=0.01*b*(b/c) , multiply both sides with c and get c^2=0.01*b^2

and we need to find:

0.01c^2=0.01*(0.01*b^2 ) - Insuf

## That's a valid solution -

That's a valid solution - nice work.

## Hi I have a question, would

## This is a very difficult

This is a very difficult question. I'd say the difficulty level of this question is above 700. On test day, you could still get this question incorrect and still score over 750. So, don't worry about it too much. That said, be sure you understand the solution, so that it may help you with similar questions.

## Fshew! Great thank you!!

## Hi Brent

At 2min into the video you simplify the (AB/100 /100) to (AB/100 * 1/100) I don't understand this step?

Wouldn't it be (AB/100 * 100/1) ?

Rules of dividing by a fraction?

Cheers

## To divide fractions, we

To divide fractions, we multiply by the reciprocal of the divisor.

That is, a/b ÷ c/d = a/b x d/c

Likewise, (a/b)(c/d) = a/b x d/c

First, (AB/100)/(100) is the same as (AB/100)/(100/1)

So, (AB/100)/(100) = (AB/100)/(100/1)

= (AB/100) x (1/100)

Does that help?

## Yes, thank you, I was

## Hi Brent,

Is this a valid approach:

Question tells us that a/100 * b = c --> ab/100=c --> ab=100c

St1) abc = 2500 --> ab =2500/c

Substitute ab with 2500/c in ab=100c --> 2500/c = 100c

Cross multiply we get 2500 = 100c^2

Divide both sides by 100 to get 25 = c^2 --> c =5 --> St1 is Suff.

St2) is not Suff.

Thanks

Aladdin

## That's a perfectly valid

That's a perfectly valid solution.

Nice work!

## Add a comment