Properties of numbers

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Properties of numbers

by saidov.mikhail » Tue Jul 23, 2013 5:52 am
For any integers x and y, min(x, y) and max(x, y) denote the minimum and the maximum of x and y, respectively. For example, min(5, 2) = 2 and max(5, 2) = 5. For the integer w, what is the value of min(10, w) ?
(1) w = max(20, z) for some integer z.
(2) w = max(10, w)

I'm confused with description of example. Why min (5,2) = 2 ?

thanks for help

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by Brent@GMATPrepNow » Tue Jul 23, 2013 6:00 am
saidov.mikhail wrote: I'm confused with description of example. Why min (5,2) = 2 ?
We refer to this as a "strange operator" question. For these question types you are introduced to some new kind of symbol. (Aside: remember when you were first introduced to the square root symbol? At first, you didn't know what it meant, and now you do.)

The strange operators here are "max" and "min."
The "max" operation basically says, "take the 2 given values in the brackets and output the greatest one.
So, for example:
max(8, 3) = 8, since 8 is the larger of the two values
max(-3, 4) = 4, since 4 is the larger of the two values
max(-1, 0) = 0, since 0 is the larger of the two values
etc.

The "min" operation says, "take the 2 given values in the brackets and output the smallest one.
So, for example:
min(8, 3) = 3, since 3 is the smaller of the two values
min(-2, 6) = -2, since -2 is the smaller of the two values
min(-5, -7) = -7, since -7 is the smaller of the two values
etc.

I hope that helps.

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Brent
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by Brent@GMATPrepNow » Tue Jul 23, 2013 6:01 am
saidov.mikhail wrote: For any integers x and y, min(x, y) and max(x, y) denote the minimum and the maximum of x and y, respectively. For example, min(5, 2) = 2 and max(5, 2) = 5. For the integer w, what is the value of min(10, w) ?

(1) w = max(20, z) for some integer z.
(2) w = max(10, w)
Target question: What is the value of min(10, w)?

Statement 1: w = max(20, z) for some integer z.
Let's take a closer look at max(20, z)
If z < 20, then max(20, z) = 20
If z > 20, then max(20, z) = some value greater than 20
So, max(20, z) must be greater than or equal to 20
Since, w = max(20, z), we can conclude that w is greater than or equal to 20
From this, we can conclude that min(10, w) = 10, since 10 will be the lesser value
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: w = max(10, w)
If w = max(10, w), then w is the larger value.
In other words, w is greater than or equal to 10
If w is greater than or equal to 10, then we can conclude that min(10, w) = 10
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = D

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by prashanthichennupati » Tue Jul 23, 2013 7:04 am
Brent: Can you please explain how statement 2 is sufficient?

Statement 2: w = max(10, w)
If w = max(10, w), then w is the larger value.
In other words, w is greater than or equal to 10
If w is greater ,then we can conclude that min(10, w) = 10
If w is equal, then how can we conclude min(10,w) =10??

Neither in the question stem nor in the statements it is mentioned that min(10,10) or max(10,10) equals 10??

Please clarify.

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Prashanthi Chennupati

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by Brent@GMATPrepNow » Tue Jul 23, 2013 7:25 am
prashanthichennupati wrote:Brent: Can you please explain how statement 2 is sufficient?

Statement 2: w = max(10, w)
If w = max(10, w), then w is the larger value.
In other words, w is greater than or equal to 10
If w is greater ,then we can conclude that min(10, w) = 10
If w is equal, then how can we conclude min(10,w) =10??

Neither in the question stem nor in the statements it is mentioned that min(10,10) or max(10,10) equals 10??

Please clarify.

Best Regards,
Prashanthi Chennupati
While the question does not explicitly tell us the value of min(10, 10), it does tell us that min(x, y) denotes the minimum value of x and y.
In other words, if we have two values (x and y) then min(x, y) will output the smallest value of the two.
So, what's the minimum (smallest) value of 10 and 10? It's 10 (if it's not 10, what is the smallest value of 10 and 10?)
So, min(10, 10) = 10

Likewise, max(x, y) denotes the maximum (biggest) value of x and y.
So, it must be true that max(10, 10) = 10

Cheers,
Brent
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by prashanthichennupati » Tue Jul 23, 2013 9:15 am
Thanks Brent.

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by [email protected] » Tue Jul 23, 2013 2:16 pm
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