need help on prep question pls

Expert replies

jc114: Senior | Next Rank: 100 Posts; Posts: 53; Joined: Thu Apr 12, 2007 12:32 am; Thanked: 1 times

by jc114 » Wed May 09, 2007 7:07 pm

OF the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had a automatic transmission but not antilock brakes?
(1) all of the cars that had antilock brakes also had an automatic transmission
(2) 2 of the cars had neither automatic transmission nor antilock brakes

Which of company x and company y earned the greater gross profit last year?

(1) last year the expenses of company x were 5/6 of the expenses of company y
(2) lat year the revenues of company x were $6 million less than the rev of company y

Like this post

Source: Beat The GMAT — Data Sufficiency | Wed May 09, 2007 7:07 pm

mendiratta: Junior | Next Rank: 30 Posts; Posts: 26; Joined: Tue May 08, 2007 8:22 pm; Thanked: 1 times

by mendiratta » Wed May 09, 2007 11:36 pm

Ist Problem: -
Ist Problem: -
1. It says "all of the cars that had antilock brakes also had an automatic transmission " that means there is no car that had either of two. So the answer is 0. Hence A.
2. It says "2 of the cars had neither automatic transmission nor antilock brakes" - Not sufficient by itself.
A.

2nd Problem: -
1. By only expenses we can't tell the profit - so this is insufficient. (Rules out A & D).
2. By only Revenues we can't tell the profit - so this is insufficient. (Rules out B).
We're left with C & E.

Combining both:-

Suppose Revenue(x) = 1
Suppose Revenue(Y) = 7

Suppose expenses of Y = 2
therefore,expenses of X = 2*5/6 = 1.66.
Clearly Profits of Y > Profits of X.

Suppose Revenue(x) = 94
Suppose Revenue(Y) = 100

Suppose expenses of Y = 60
therefore,expenses of X = 60*5/6 = 50.
So, Profits of Y = 40
So, Profits of X = 44
Clearly Profits of X > Profits of Y.

So answer is E.

Like this post

mschling52: Master | Next Rank: 500 Posts; Posts: 105; Joined: Mon Sep 18, 2006 12:34 pm; Location: OH; Thanked: 7 times; GMAT Score:780

by mschling52 » Thu May 10, 2007 5:22 am

For Question 1, I think the answer is E.

(1)If we picture a Venn diagram, statement (1) tells us that the circle representing AntiLock Brakes is within the circle representing Automatic Transmission, but not that they are necessarily the same size (i.e. Venn Diagram could look like a bullseye with one circle inside the other). In other words, all cars with AntiLock Brakes have Automatic Transmission, but this does not imply that all cars with Automatic Transmission have AntiLock Brakes. Essentially this leaves us with 3 categories: Cars with neither ALB or AT, Cars with both ALB and AT, and Cars with AT but not ALB. We are interested in the last group. NOT SUFFICIENT

(2)From this we know that there are 2 cars on the outside of the circles in our Venn Diagram, so 23 have ALB, AT, or BOTH, but we know nothing more. NOT SUFFICIENT.

(1)&(2) Statement (1) gave us 3 categories and Statement (2) tells us the value of 1 of them, but we still have 2 groups (Cars with BOTH and Cars with AT but not ALB) that make up the remaining 23 cars. No way to tell how much of the 23 goes to either group. NOT SUFFICIENT.

Like this post

jayhawk2001: Community Manager; Posts: 789; Joined: Sun Jan 28, 2007 3:51 pmFollowed by: 1 member; Location: Silicon valley, California; Thanked: 30 times

Re: need help on prep question pls

by jayhawk2001 » Thu May 10, 2007 7:07 am

1 - E

2 - E

Like this post

wizardofwashington: Senior | Next Rank: 100 Posts; Posts: 71; Joined: Wed Aug 22, 2007 12:29 pmFollowed by: 1 member; Location: USA; Thanked: 12 times

Re: need help on prep question pls

by wizardofwashington » Sun May 18, 2008 7:48 pm

jc114 wrote:OF the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had a automatic transmission but not antilock brakes?
(1) all of the cars that had antilock brakes also had an automatic transmission
(2) 2 of the cars had neither automatic transmission nor antilock brakes

Which of company x and company y earned the greater gross profit last year?

(1) last year the expenses of company x were 5/6 of the expenses of company y
(2) lat year the revenues of company x were $6 million less than the rev of company y

For what it is worth, I had this very same question in my real GMAT exam.

A falling tree resounds... but a forest grows in silence...

Like this post

netigen: Legendary Member; Posts: 631; Joined: Mon Feb 18, 2008 11:57 pmFollowed by: 3 members; Thanked: 29 times

by netigen » Sun May 18, 2008 8:33 pm

Ans should be

(1) E
(2) E

Like this post

Stuart@KaplanGMAT: GMAT Instructor; Posts: 3225; Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members; Location: Toronto; Thanked: 1710 times; GMAT Score:800

by Stuart@KaplanGMAT » Mon May 19, 2008 9:10 am

mendiratta wrote:Ist Problem: -
Ist Problem: -
1. It says "all of the cars that had antilock brakes also had an automatic transmission " that means there is no car that had either of two. So the answer is 0. Hence A.

"All A are B" does NOT necessarily mean that "All B are A".

For example, "All the animals that have 4 legs also have 2 eyes" does not mean that "all the animals that have 2 eyes also have 4 legs".

So, statement (1) tells us that every car in the antilock group is also in the autamatic group, but NOT vice-versa. As a result, we have too many variables to solve, even with statement (2).

If we had written the original overlapping sets formula:

True # = (# with characteristic 1) + (# with characteristic 2) + (# with neither) - (# with both)

25 = antilock + automatic + neither - both

And the question is: "what is automatic - both?"

(1) lets us know that antilock = both, but no real numbers: insufficient.

(2) 25 = antilock + automatic + 2 - both

23 - antilock = automatic - both

Still one too many variables: insufficient.

Together:

knowing that antilock = both, we can substitute:

23 - both = automatic - both
23 = automatic.

However, the question isn't asking us to solve for the total # with automatic transmissions, it's asking us how many cars have ONLY automatic transmissions, i.e. "auto - both".

With the info we have, both could be any number from 1-23, so there's no way to solve: choose (e).

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

Like this post

akshatsingh: Senior | Next Rank: 100 Posts; Posts: 77; Joined: Thu Apr 10, 2008 10:13 pm; Thanked: 4 times

by akshatsingh » Tue May 20, 2008 2:00 am

Hi can you please post the source of these questions.

They are good.. would want to see other problems there too..

Thanks in advance

Aks

Like this post

gkumar: 2009 Beat The GMAT Scholarship Winner; Posts: 182; Joined: Sat Mar 22, 2008 7:35 pmFollowed by: 2 members; Thanked: 3 times; GMAT Score:700+

by gkumar » Sun Oct 18, 2009 2:32 pm

I tried tackling the first problem using the MGMAT Double Matrix method but I got the wrong answer. Stuart, can you please clarify my error?

I have the below Matrix from the question stem?
Automatic Non-Automatic Total
Antilock Z=?
Non-AL
Total 25

Statement 1 gives:
___________| Automatic | Non-Automatic | Total
Antilock ____| __ X ____ | ____ Z=? ___ | X+Z
Non-AL ____| __ 0 ____ | ____ ? _____ | ?
Total ______| __ X ____ | ____ Y ______ | 25

We know nothing about variables X and Y so we cannot find Z for which the question is asking. Statement 1 is eliminated.

Statement 2 gives:
___________| Automatic | Non-Automatic | Total
Antilock ____| __ X ____ | ____ Z=? ___ | X+Z
Non-AL ____| __ ? ____ | ____ 2 _____ | ?+2
Total ______| __ X+?___ | ____ Y=2+Z __ | 25

We know nothing about variables X and Y so we cannot find Z for which the question is asking. Statement 2 is eliminated.

Statement 1 and 2 gives:
___________| Automatic | Non-Automatic | Total
Antilock ____| __ X ____ | ____ Z=? ___ | X+Z=23
Non-AL ____| __ 0 ____ | ____ 2 _____ | 2
Total ______| __ X ____ | ____ Y=2+Z __ | 25

The following equations can be made:
X+Z=23
Y-Z=2
X+Y=25

We have three equations and three variables. So the system of equations should be solvable to obtain Z. So I assumed the answer to be C. But the answer is E. Where did I go wrong?

Like this post

Talkativetree: Senior | Next Rank: 100 Posts; Posts: 43; Joined: Tue Oct 13, 2009 3:31 pm

Re: need help on prep question pls

by Talkativetree » Sun Oct 18, 2009 2:51 pm

jc114 wrote:OF the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had a automatic transmission but not antilock brakes?
(1) all of the cars that had antilock brakes also had an automatic transmission
(2) 2 of the cars had neither automatic transmission nor antilock brakes

You know from (2) that 23 cars had either an automatic trans. or anti lock breaks, but by itself is insufficient

From (1), we know that all of the cars with antilock brakes also have an automatic transmissions. This by itself doesn't tell us is how many of the cars had only automatic transmissions. so this by itself is insufficient.

(1) and (2) combined doesn't tell us anything else either. When a question says some, some can mean all of the cars, or just 1 of the cars. so (1) might be saying that all 23 cars have both, but it might also be saying that only 10 cars have both. Because we are still unsure, answer is E imo.

jc114 wrote:Which of company x and company y earned the greater gross profit last year?

(1) last year the expenses of company x were 5/6 of the expenses of company y
(2) lat year the revenues of company x were $6 million less than the rev of company y

Another E I think, but I'll work this out.

Looking briefly at both (1) and (2), you are not actually given what the revenue or the expenses of the company are, so while you may be able to come up with equations like 5/6(x exp.)=(y exp) or X rev - 6mil = y rev, we are still in the dark. The expense of y could have been 600,000,000 and it's revenue could have bee 500,000,000. This would mean that X's expenses would have been 500,000,000. However, the revenue of X would have been 494,000,000. meaning company X lost 6million, but company y lost 100,000,000. .

Hope this all helps

Like this post

gkumar: 2009 Beat The GMAT Scholarship Winner; Posts: 182; Joined: Sat Mar 22, 2008 7:35 pmFollowed by: 2 members; Thanked: 3 times; GMAT Score:700+

by gkumar » Sun Oct 18, 2009 3:15 pm

Yes, your logic using a venn diagram-like approach certainly makes sense.

But why did my system of equations lead me to a false answer?

Like this post

Talkativetree: Senior | Next Rank: 100 Posts; Posts: 43; Joined: Tue Oct 13, 2009 3:31 pm

by Talkativetree » Sun Oct 18, 2009 4:06 pm

you actually only have two equations hidden in 3 I believe. Let's subsitute.

X+Z=23
Y-Z=2
X+Y=25

Y-Z=2
Z=Y-2

X+Z=23
X + (Y-2)=23
X + Y = 25

Like this post

gkumar: 2009 Beat The GMAT Scholarship Winner; Posts: 182; Joined: Sat Mar 22, 2008 7:35 pmFollowed by: 2 members; Thanked: 3 times; GMAT Score:700+

by gkumar » Sun Oct 18, 2009 4:21 pm

Doh! Thanks talkativetree! I am glad that you are quite talkative, lol

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review