Inference

This topic has expert replies
User avatar
Master | Next Rank: 500 Posts
Posts: 423
Joined: Thu Dec 27, 2007 1:29 am
Location: Hyderabad, India
Thanked: 36 times
Followed by:2 members
GMAT Score:770

by simplyjat » Tue Jan 29, 2008 8:49 pm
sibbineni wrote:OA is A
I have google and thus know about OA. But can you explain the answer, none of the posts, which are full of silly mistakes, seems to be explaining the answer.
simplyjat

User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Tue Jan 29, 2008 10:07 pm
simplyjat wrote:
sibbineni wrote:OA is A
I have google and thus know about OA. But can you explain the answer, none of the posts, which are full of silly mistakes, seems to be explaining the answer.
Heh, the posts are not full of silly mistakes, you're just not understanding them :D

Let's try once more:
Recent estimates predict that between 1982 and 1995 the greatest increase in the number of people employed will be in the category of low-paying service occupations. This category, however, will not increase its share of total employment, whereas the category of high-paying service occupations will increase its share.
If the estimates above are accurate, which of the following conclusions can be drawn?

(A) In 1982 more people were working in low-paying service occupations than were working in high-paying service occupations.
(B) In 1995 more people will be working in high-paying service occupations than will be working in low-paying service occupations.
(C) Nonservice occupations will account for the same share of total employment in 1995 as in 1982.
(D) Many of the people who were working in low-paying service occupations in 1982 will be working in high-paying service occupations by 1995.
(E) The rate of growth for low-paying service occupations will be greater than the overall rate of employment growth between 1982 and 1995.
We have three facts to reconcile:

(1) the greatest increase in the number of people employed will be in low-paying service jobs;

(2) low paying service jobs will not increase their share of total employment; and

(3) high paying service jobs will increase their share of total employment.

Let's start with (1) and (2).

If the # of low paying service jobs increases but their share of the market does not, then other sectors of the market have to increase by a greater number.

Now let's look at (3) by itself.

If high paying service jobs does increase their share of the market, then there are two possibilities. First, there are more high paying service jobs relative to new types of other jobs; or second, the number of other jobs decrease (and the number of high paying service jobs could increase, remain stagnant or go down, but by proportionally less).

Finally, let's combine (1), (2) and (3).

If we know that the number of low paying service jobs went up by a greater number than any other type of job, but did not gain market share, then we know that simply gaining #s isn't enough. Somehow, however, high paying service jobs did gain market share, even though fewer high paying service jobs were created than low paying service jobs.

The ONLY way these facts can be reconciled is if we started with more low paying service jobs in the first place, so that even if the number of high paying service jobs went up by less, the number of high paying service jobs went up by proportionally more.

Looking at it mathematically:

let l = # of low paying service jobs in 1982
let x = # of new low paying service jobs from 1982-1995
let h = # of high paying service jobs in 1982
let y = # of new high paying service jobs from 1982-1995
let t = total number of jobs in 1982
let z = total # of new jobs from 1982-1995

From the stimulus, we know that:

l/t >= (l+x)/(t+z)

and

h/t < (h+y)/(t+z)

and

x > y

The only way that all of those inequalities can be true is if l > h

So, (a) must be correct.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course

Legendary Member
Posts: 1404
Joined: Tue May 20, 2008 6:55 pm
Thanked: 18 times
Followed by:2 members

by tanviet » Tue Oct 20, 2009 11:57 pm
this question is wrong because it dose not say that there are only 2 kinds of employee, low paying and high paying

GMAT Instructor
Posts: 1302
Joined: Mon Oct 19, 2009 2:13 pm
Location: Toronto
Thanked: 539 times
Followed by:164 members
GMAT Score:800

by Testluv » Wed Oct 21, 2009 7:50 pm
It does not have to. The category of middle payment, whether or not it exists, is irrelevant. It can simply be lumped in with "other" sectors.

Stuart's explanation is excellent, and I would suggest that it should be studied carefully (before being criticized.)

This is a valid GMAT style question. The GMAT loves to test your quant skills in verbal and your verbal skills in quant.

As an aside, simpljat's (unfortunately, in this case, questionable) reason for rejecting A (that it deals with numbers) is also why he should reject D (because D also deals with numbers).

Master | Next Rank: 500 Posts
Posts: 200
Joined: Sat Aug 22, 2015 10:27 am

by james33 » Sun May 15, 2016 9:58 pm
Answer A seems to be logical one out of other answer choices