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xcise_science: Master | Next Rank: 500 Posts; Posts: 106; Joined: Tue Oct 09, 2007 12:25 pm; Thanked: 1 times

gmat prep problems

by xcise_science » Tue Nov 20, 2007 7:59 pm

Hello all,
Can someone please explain these questions?

Thanks!

#7

Answer is A

#36

Answer is C

#19

Answer is C

#29

Answer is C

#28
Answer is D

#30
Answer is D

Quote

Source: Beat The GMAT — Data Sufficiency | Tue Nov 20, 2007 7:59 pm

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

by jayhawk2001 » Thu Nov 22, 2007 8:17 am

Hi, please post 1 or 2 questions in each post. This will
encourage discussion amongst the members.

For question 7,

1 - sufficient. Angle BAD = Angle ABD = x (since exterior angle = 2x).
So, ABD is isosceles with AD = BD. We also know BD = BC since
triangle BDC is isosceles.

2 - insufficient. We have no knowledge of length of any of the
sides.

Hence A

Quote

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

by jayhawk2001 » Thu Nov 22, 2007 8:24 am

For question 36 --

Let target for Jan = I. We need to know I and x to solve (I + 2x) for
march

1 - insufficient.
Target Dec = I + 11x = 310000. We don't know I and x

2 - insufficient.
I + 8x = 30000 + I + 5x. We can find x but we still don't know I

Combining, we have 2 equations with 2 variables. Hence we
can solve for I and x.

Quote

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

by jayhawk2001 » Thu Nov 22, 2007 8:27 am

For question 19 --

1 - insufficient. We just know a+b=-1. We need to find a and b since
these are the 2 points at which the graph cuts the x-axis

2 - insufficient. We just know ab=-6 (substitute for x, y in eqn)

Together we can find a and b and hence is sufficient.

Answer is C.

Quote

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

by jayhawk2001 » Thu Nov 22, 2007 8:32 am

For question 28 --

If total budget = x, dollars in radio budget = 7 / 20 * x

1 - sufficient. we have 8/20*x = 18750 + 3/20*x. We can solve
for x

2 - sufficient. same as 1

Hence D

Quote

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

by jayhawk2001 » Thu Nov 22, 2007 8:35 am

For question 30 --

Let there be 'n' chairs in each row. We have n * (n-1) chairs in all

1 - sufficient. n * (n-1) = 72. n has to be integer, so we can solve for n

2 - sufficient. n + n-1 = 17. Again we can solve for n

Hence D

Quote

sujaysolanki: Master | Next Rank: 500 Posts; Posts: 214; Joined: Wed Nov 14, 2007 6:30 am; Thanked: 15 times

by sujaysolanki » Thu Nov 22, 2007 8:39 am

This is based on the exterior angle property of a triangle

Ext = sum of 2 int opposite angles

Angle BAD = Angle ABD = x Hence AD = BD

Angle BDC = Angle BCD Hence BD = BC = 6

Hence A ...

Quote

xcise_science: Master | Next Rank: 500 Posts; Posts: 106; Joined: Tue Oct 09, 2007 12:25 pm; Thanked: 1 times

by xcise_science » Sat Nov 24, 2007 11:29 am

Thanks alot for the explanations. Most of my problems are in setting up equations (as you did in Q28,30, 36).

For Q7, when you say exterior angles, are you referring to angles BDC + BCD (which sum to = angle BAD?)

Also, where can I find more information regarding triangle properties?

Thanks!

Quote

sujaysolanki: Master | Next Rank: 500 Posts; Posts: 214; Joined: Wed Nov 14, 2007 6:30 am; Thanked: 15 times

by sujaysolanki » Sat Nov 24, 2007 9:52 pm

Could someone please explain how we go about 29 ..i guess that has been overlooked

Quote

lawalx: Senior | Next Rank: 100 Posts; Posts: 42; Joined: Tue Nov 06, 2007 10:39 am

by lawalx » Sun Nov 25, 2007 11:29 pm

i dont knw if ul consider this a proper explanation but il try.

lets say in '95 K's salary is 10,000 and J's - 8000
the difference in their salaries is 2000

then in '98 their salaries increased by 20%
This gives K - 12000 and J - 9600
the diff is 2400

since both salaries were increased by the same % the diff in their salaries ifor the 2 years will show the percentage increase over the 2 year -
i.e. 2400 - 2000 = 400
then 400/2000 * 100 = 20%
which is the percentage increase in their respective salaries over the yrs. u can try this by inputin other figures

so back to the question - since (1) gives u the diff in one year and (2) gives u the diff in the other year

then 2440 - 2000 = 440
440/2000 * 100 = p = 22%

i hope u gt?

correct me if im wrong

Quote

sujaysolanki: Master | Next Rank: 500 Posts; Posts: 214; Joined: Wed Nov 14, 2007 6:30 am; Thanked: 15 times

by sujaysolanki » Mon Nov 26, 2007 8:32 am

I am not too sure i think it shd be be E ..i posted it on mgmat forum for confirmation ..heres the link

https://www.manhattangmat.com/forums/post5866.html#5866

Quote

xcise_science: Master | Next Rank: 500 Posts; Posts: 106; Joined: Tue Oct 09, 2007 12:25 pm; Thanked: 1 times

by xcise_science » Mon Nov 26, 2007 9:14 am

No, E was my original answer, which was wrong, the answer is C.

Quote

xcise_science: Master | Next Rank: 500 Posts; Posts: 106; Joined: Tue Oct 09, 2007 12:25 pm; Thanked: 1 times

by xcise_science » Mon Nov 26, 2007 9:58 am

I'm not really clear on your explanation.

I mean, I understand this part:
so back to the question - since (1) gives u the diff in one year and (2) gives u the diff in the other year
then 2440 - 2000 = 440
440/2000 * 100 = p = 22%

But I'm not really sure I understand this:

then in '98 their salaries increased by 20%
This gives K - 12000 and J - 9600
the diff is 2400
since both salaries were increased by the same % the diff in their salaries ifor the 2 years will show the percentage increase over the 2 year -
i.e. 2400 - 2000 = 400

Can't you just calculate the percent change using the 2440 & 2000?

thanks

Quote

gabriel: Legendary Member; Posts: 986; Joined: Wed Dec 20, 2006 11:07 am; Location: India; Thanked: 51 times; Followed by:1 members

by gabriel » Mon Nov 26, 2007 10:03 am

lawalx wrote:i dont knw if ul consider this a proper explanation but il try.

lets say in '95 K's salary is 10,000 and J's - 8000
the difference in their salaries is 2000

then in '98 their salaries increased by 20%
This gives K - 12000 and J - 9600
the diff is 2400

since both salaries were increased by the same % the diff in their salaries ifor the 2 years will show the percentage increase over the 2 year -
i.e. 2400 - 2000 = 400
then 400/2000 * 100 = 20%
which is the percentage increase in their respective salaries over the yrs. u can try this by inputin other figures

so back to the question - since (1) gives u the diff in one year and (2) gives u the diff in the other year

then 2440 - 2000 = 440
440/2000 * 100 = p = 22%

i hope u gt?

correct me if im wrong

I am not sure I agree with your answer .. how did u get to the conclusion that both of them increase by the same amount ..

for eg .... karens salay in 95 = 10000 and Jasons's is 8000, now in 98 karens salary could be 10001 and Jason's will be 7561

Or

Karen's Salary in 98 is 10000 and Jason's is 8000, in 98 Karens could be 25000 and Jasons will be 22560 ..

so we basically cannot find out p even with both the statements combined .. so me also going for E .. am in a hurry, will take a look at the question once again, but right now am sticking with E .. can others answer too ..