Brain shutdown on averages

[oquiella]

35. Is Johnson more than 40 years of age?
(1) The average age of 20 employees in Johnson's office is 48.
(2) Johnson is among the 3 oldest employees in his office in which the age of
retirement is 60 years

A: C

Explain the math in steps please

[[email protected]]

Hi oquiella,

You've posted a number of questions recently that are of questionable quality/design. Did any of these questions include an actual explanation? And why are you continuing to use them (there are LOTS of reputable sources for practice questions).

GMAT assassins aren't born, they're made,
Rich

[oquiella]

Hi oquiella,

You've posted a number of questions recently that are of questionable quality/design. Did any of these questions include an actual explanation? And why are you continuing to use them (there are LOTS of reputable sources for practice questions).

GMAT assassins aren't born, they're made,
Rich

Hi Rich,

I have extracted thes questions directly from Aristotle DS Booster problems. I heard so many good reviews but now am finding errors in the PDF file itself and now according to some ecperts on here within the DS questions. Is this no longer a viable source? I see many users have praised this resource for extra practice. Please advise.

[GMATGuruNY]

35. Is Johnson more than 40 years of age?
(1) The average age of 20 employees in Johnson's office is 48.
(2) Johnson is among the 3 oldest employees in his office in which the age of
retirement is 60 years

Statement 1:
Sum of the ages = (number of employees)(average age) = 20*48 = 960.
Here, it's possible that J=40 or that J>40.
INSUFFICIENT.

Statement 2:
Since the age of retirement is 60, it's possible that J=40 or that J>40.
INSUFFICIENT.

Statements combined:
Let the 3 oldest employees be J, K and L.
Test whether it's possible that J=40.

Since the age of retirement is 60, the maximum possible age for K and L is 60.
Since J, K and L are the 3 oldest -- and J=40 -- the maximum possible age for each of the remaining 17 employees = 39.
Thus:
Maximum possible sum of all of the ages = (sum of the greatest possible ages for J, K and L) + (sum of the greatest possible ages for the remaining 17 employees) = (40+60+60) + (17*39) = 160 + 663 = 823.
Not viable:
The sum of the ages must be 960.

Since J=40 yields a maximum sum that is TOO SMALL, J's age must be GREATER THAN 40.
SUFFICIENT.

The correct answer is C.

[[email protected]]

Hi oquiella,

Your study time is so valuable that you shouldn't be spending it with resources that are flawed, poorly-designed and without proper explanations. There are countless better resources that you can be using right now, if you choose to.

As an aside, where have you read the 'praise' for this material (from MANY users)?

GMAT assassins aren't born, they're made,
Rich

[oquiella]

Hi oquiella,

Your study time is so valuable that you shouldn't be spending it with resources that are flawed, poorly-designed and without proper explanations. There are countless better resources that you can be using right now, if you choose to.

As an aside, where have you read the 'praise' for this material (from MANY users)?

GMAT assassins aren't born, they're made,
Rich

I searched through beat the GMAT forum for people who received atleast 760 + on GMAT and they all referenced Aristotle PS and DS Boosters for extra practice with Manhattan GMAT advanced Quant. Do you know of any specific sources I can use for 700+ difficulty level questions?

[Matt@VeritasPrep]

I don't know anything about Aristotle, so their materials might be great and the reviews could be real, but I'm skeptical of anything lauded online these days: you never know who's actually writing the review. Whenever possible, try to preview the material and decide for yourself whether it's any good.