Have questions about your preparation or an upcoming test? Need help modifying the Study Plan to meet your unique needs? No problem. Just book a Skype meeting with Brent to discuss these and any other questions you may have.

- Video Course
- Video Course Overview
- General GMAT Strategies - 7 videos (free)
- Data Sufficiency - 16 videos (free)
- Arithmetic - 38 videos
- Powers and Roots - 36 videos
- Algebra and Equation Solving - 73 videos
- Word Problems - 48 videos
- Geometry - 42 videos
- Integer Properties - 38 videos
- Statistics - 20 videos
- Counting - 27 videos
- Probability - 23 videos
- Analytical Writing Assessment - 5 videos (free)
- Reading Comprehension - 10 videos (free)
- Critical Reasoning - 38 videos
- Sentence Correction - 70 videos
- Integrated Reasoning - 17 videos

- Study Guide
- Your Instructor
- Office Hours
- Extras
- Prices

## Comment on

Socks## What are the question should

## You'll find the answer to

You'll find the answer to that question at the bottom of https://www.gmatprepnow.com/module/gmat-probability

## Hey, thanks for the videos,

For this question, considering statement 2, if we solve the equation for W, which is W^2 - W - 12 > 0, I get the following 2 results:

W > -3

W > 4

Now if we use W>4, we can arrive the answer that the statement is sufficient. My question is that can we disregard W > -3? By this equation, W can also be 1,2,3...and so on. Please explain

## Be careful.

Be careful.

When we solve the inequality W^2 - W - 12 > 0, we get first get (W - 4)(W + 3) > 0

When we solve, we get: W > 4 or W < -3 (less than -3, not greater than -3)

For more on solving quadratic inequalities, watch: https://www.gmatprepnow.com/module/gmat-algebra-and-equation-solving/vid...

If W < -3, then some possible values of W are -4, -5, -6, -7, etc.

None of these values fit the requirement that W must be an integer that's greater than or equal to zero.

## Poorly written question,

Be careful.

## That's intentional. We don't

That's intentional. We don't need the proviso that the socks are black and white only. In fact, there's no reason why there can't be socks of other colors, but it doesn't change the answer.

## Its a very good question. can

## I'd say that it's a 700+

I'd say that it's a 700+ level question.

## Great trick. Remainder of why

## I think if there are more

## Hi ideree,

Hi ideree,

Many students have suggested this. However, it makes no difference whether there are socks a color different from white or black.

If you're not convinced, try to find a scenario in which a 3rd color makes statement 2 insufficient.

Cheers,

Brent

## Wonderful Question :)

## Does it help to know through

## Statement 2 helps us reduce

Statement 2 helps us reduce the possible number of black socks. It indirectly tells us that there are either 0 or 1 black socks.

If there are 0 black socks, then it's impossible to select 2 black socks without replacement.

So, the answer to the target question is, "The probability is 0 that we select 2 black sock with replacement"

If there is 1 black sock, then it's impossible to select 2 black socks without replacement.

So, the answer to the target question is, "The probability is 0 that we select 2 black sock with replacement"

So, statement 2 is sufficient.

## You mean Statement 2 is

## Oops - good catch!!

Oops - good catch!!

I edited my response.

Cheers,

Brent

## Hi Brent,

Could you please provide a solution to this question,

After reading a few comments I still don't understand it:

https://gmatclub.com/forum/tanya-prepared-4-different-letters-to-be-sent-to-4-different-addresses-85167.html

Thank you in advance,

## Hi Kirill,

Hi Kirill,

Here's my full solution: https://gmatclub.com/forum/tanya-prepared-4-different-letters-to-be-sent...

## Hi Brent,

Thank you very much,

## Hi brent,

Can you elaborate how can we assume there are no more than 2 colors for socks ?

Thanks,

Karaan

## Hi Karaan,

Hi Karaan,

We don't necessarily know there are only 2 colors.

From statement 1, we know that the drawer contains either 1 black sock or 0 black socks.

From statement 2, we know that the drawer contains either 5 white socks or 6 white socks.

When we combine the statements we see that there are exactly three possible outcomes:

1) 1 black sock, and 5 white socks

2) 0 black socks, and 6 white socks

3) 0 black socks, 5 white socks and 1 other sock

Having said that, all that really matters is that we don't have 2 black socks, which means P(selecting 2 black socks) = 0

Cheers,

Brent

## hi Brent,

Could you please solve this question?

Matt is touring a nation in which coins are issued in two amounts, 2¢ and 5¢, which are made of iron and copper, respectively. If Matt has ten iron coins and ten copper coins, how many different sums from 1¢ to 70¢ can he make with a combination of his coins?

A. 66

B. 67

C. 68

D. 69

E. 70

Thanks

## I've included the answer

I've included the answer choices since they're crucial to solving the question.

First notice that there's no way to get sums of 1¢ and 3¢

Now notice that we can't get sums of 69¢ and 67¢

How do we know this?

Since we have a total of 70¢, we'd need to remove a 1¢ coin to get a sum of 69¢. Since there are no 1¢ coins, we can't get 69¢.

Similarly, we'd need to remove a 3¢ coin to get a sum of 67¢. Since there are no 3¢ coins, we can't get 67¢.

There are 70 values from 1¢ to 70¢ inclusive.

We can't make 4 sums (1¢, 3¢, 67¢ and 69¢)

70 - 4 = 66

So there must be a total of 66 possible sums.

Answer: A

## Thanks, Bret. Your solutions

A tank is filled with gasoline to a depth of exactly 2 feet. The tank is a cylinder resting horizontally on its side, with its circular ends oriented vertically. The inside of the tank is exactly 6 feet long. What is the volume of gasoline in the tank?

(1) The inside of the tank is exactly 4 feet in diameter.

(2) The top surface of the gasoline forms a rectangle that has an area of 24 square feet.

Thank you! :)

## Karishma has a great solution

Karishma has a great solution (with diagrams) here: https://gmatclub.com/forum/a-tank-is-filled-with-gasoline-to-a-depth-of-...

Let me know if you have any questions about her solution.

Cheers,

Brent

## Hey Brent,

Do you have a visual solution of this using venn diagrams?

https://gmatclub.com/forum/let-s-be-a-set-of-outcomes-and-let-a-and-b-be-events-with-outcomes-in-305932.html

## Here's my full solution using

Here's my full solution using the Double Matrix method: https://gmatclub.com/forum/let-s-be-a-set-of-outcomes-and-let-a-and-b-be...

## Add a comment