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# DS: A. Is m+ z > 0? 1. m-3z>0 2. 4z -m >0 B. At

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DS: A. Is m+ z > 0? 1. m-3z>0 2. 4z -m >0 B. At [#permalink]  17 Aug 2008, 18:19
DS:
A. Is m+ z > 0?
1. m-3z>0
2. 4z -m >0

B. At least 100 students at a certain high school study Japanese. If 4 percent of the students at the school who study French also study Japanese, do more students at the school study French than Japanese?
1. 16 students at the school study both French and Japanese.
2. 10 percent of the students at the school who study Japanese also study French.

C. If the terms of a sequence are t1, t2, t3,....tn what is the value of n?
1. The sum of the n terms is 3124.
2. The average of the n terms is 4.

D. Of the 1400college teachers surveyed, 42% said that they considered engaging in research as essential goal. HOw many of the college teachers surveyed were women?
1. In the survey, 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said that they considered engaging in research an essential goal.

PS:
E. A committee of 3 people is to be chosen from 4 married couples. What is the number of different committes that can be chosen if 2 people who are married to each other cannot both serve on the committee?
16/24/26/30/32

TIA.
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Re: GMAT Prep - Need explanations too. [#permalink]  17 Aug 2008, 20:05
DS:
A. Is m+ z > 0?
1. m-3z>0
2. 4z -m >0

C.
1. m-3z>0 .........................i
2. 4z -m >0 ....................... ii

C. from i and ii, z > 0. so suff.
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Re: GMAT Prep - Need explanations too. [#permalink]  17 Aug 2008, 20:13
B. At least 100 students at a certain high school study Japanese. If 4 percent of the students at the school who study French also study Japanese, do more students at the school study French than Japanese?

1. 16 students at the school study both French and Japanese.
2. 10 percent of the students at the school who study Japanese also study French

1: 16 students at the school study both French and Japanese is equivalant to 4% of total french student.
so french student = 400 but we do not know the no of student who study japanese. nsf..

2. 10 percent of the students at the school who study Japanese also study French is equivalant to 4 percent of the students at the school who study French also study Japanese.

i.e. 10% of japanese = 4% of french.
so F > J.

suff

B..
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Re: GMAT Prep - Need explanations too. [#permalink]  17 Aug 2008, 21:20
D. Of the 1400 college teachers surveyed, 42% said that they considered engaging in research as essential goal. How many of the college teachers surveyed were women?

1. In the survey, 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said that they considered engaging in research an essential goal.

Total College teachers surveyed = t = m + w = 1400
Men College teachers surveyed = m
Women College teachers surveyed = w
College teachers who were surveyed and considered engaging in research as essential goal = c = 42% of 1400 = 588
Men College teachers who were surveyed and considered engaging in research as essential goal = ms
Women College teachers who were surveyed and considered engaging in research as essential goal = ws

so, ws = ?

1: ms = 36% of m
ws = 50% of w
36% of m + 50% of w = 588. nsf..

2: In the survey, 288 men said that they considered engaging in research an essential goal.

togather: ms = 288 which is 36% of m
288 = 36% of m
m = 288/0.36% = 800
w = 600

so C. suff.
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Re: GMAT Prep - Need explanations too. [#permalink]  17 Aug 2008, 21:42
E. A committee of 3 people is to be chosen from 4 married couples. What is the number of different committes that can be chosen if 2 people who are married to each other cannot both serve on the committee?
16/24/26/30/32

total = 3 out of 8 = 8c3 = 8x7x6x5! / (5!x3!) = 8x7 = 56
3 with a couple and 1 single = 4c1 x 6 = 24
3 without a couple = 56 - 24 = 32
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Re: GMAT Prep - Need explanations too. [#permalink]  20 Aug 2008, 19:08
GMAT TIGER wrote:
D. Of the 1400 college teachers surveyed, 42% said that they considered engaging in research as essential goal. How many of the college teachers surveyed were women?

1. In the survey, 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said that they considered engaging in research an essential goal.

Total College teachers surveyed = t = m + w = 1400
Men College teachers surveyed = m
Women College teachers surveyed = w
College teachers who were surveyed and considered engaging in research as essential goal = c = 42% of 1400 = 588
Men College teachers who were surveyed and considered engaging in research as essential goal = ms
Women College teachers who were surveyed and considered engaging in research as essential goal = ws

so, ws = ?

1: ms = 36% of m
ws = 50% of w
36% of m + 50% of w = 588. nsf..

2: In the survey, 288 men said that they considered engaging in research an essential goal.

togather: ms = 288 which is 36% of m
288 = 36% of m
m = 288/0.36% = 800
w = 600

so C. suff.

I agree to the above exp. but OA is A.
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Re: GMAT Prep - Need explanations too. [#permalink]  20 Aug 2008, 19:12
GMAT TIGER wrote:
E. A committee of 3 people is to be chosen from 4 married couples. What is the number of different committes that can be chosen if 2 people who are married to each other cannot both serve on the committee?
16/24/26/30/32

total = 3 out of 8 = 8c3 = 8x7x6x5! / (5!x3!) = 8x7 = 56
3 with a couple and 1 single = 4c1 x 6 = 24
3 without a couple = 56 - 24 = 32

Ans is correct.

But -> 3 with a couple and 1 single = 4c1 x 6 = 24. I didnt understand this, can you pls explain.
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Re: GMAT Prep - Need explanations too. [#permalink]  20 Aug 2008, 21:27
GMAT TIGER wrote:
D. Of the 1400 college teachers surveyed, 42% said that they considered engaging in research as essential goal. How many of the college teachers surveyed were women?

1. In the survey, 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said that they considered engaging in research an essential goal.

Total College teachers surveyed = t = m + w = 1400
Men College teachers surveyed = m
Women College teachers surveyed = w
College teachers who were surveyed and considered engaging in research as essential goal = c = 42% of 1400 = 588
Men College teachers who were surveyed and considered engaging in research as essential goal = ms
Women College teachers who were surveyed and considered engaging in research as essential goal = ws

so, ws = ?

1: ms = 36% of m
ws = 50% of w
36% of m + 50% of w = 588. nsf..

2: In the survey, 288 men said that they considered engaging in research an essential goal.

togather: ms = 288 which is 36% of m
288 = 36% of m
m = 288/0.36% = 800
w = 600

so C. suff.

I agree to the above exp. but OA is A.

lets do it again

Men College teachers surveyed = m
Women College teachers surveyed = w
Total College teachers surveyed = t = m + w = 1400

Men College teachers surveyed = m = 1400 - w
Women College teachers surveyed = w = 1400 - m

College teachers who were surveyed and considered engaging in research as essential goal = c = 42% of 1400 = 588
Men College teachers who were surveyed and considered engaging in research as essential goal = ms
Women College teachers who were surveyed and considered engaging in research as essential goal = ws

so, ws = ?

1: ms = 36% of m
ws = 50% of w
36% of m + 50% of w = 588
36% of m + 50% of (1400 - m) = 588
36% of m + 50% of (1400 - m) = 588
m = 800 and w = 600.
suff........................

2: In the survey, 288 men said that they considered engaging in research an essential goal.

so A. suff.
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Re: GMAT Prep - Need explanations too. [#permalink]  20 Aug 2008, 21:30
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GMAT TIGER wrote:
E. A committee of 3 people is to be chosen from 4 married couples. What is the number of different committes that can be chosen if 2 people who are married to each other cannot both serve on the committee?
16/24/26/30/32

total = 3 out of 8 = 8c3 = 8x7x6x5! / (5!x3!) = 8x7 = 56
3 with a couple and 1 single = 4c1 x 6 = 24
3 without a couple = 56 - 24 = 32

Ans is correct.

But -> 3 with a couple and 1 single = 4c1 x 6 = 24. I didnt understand this, can you pls explain.

3 people includes a couple and a single = (no of ways a couple can be selected) x (no of ways a single can be selected)
3 people includes a couple and a single = (a couple can be selected out of 4 couple in 4 ways) x (a single can be selected in 6 ways out of 6 people after selected a couple)
3 people includes a couple and a single = 4c1 x 6
3 people includes a couple and a single = 24
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Re: GMAT Prep - Need explanations too. [#permalink]  21 Aug 2008, 12:14
whats the ans for the 1st DS

i think it shud be E :

1 m>3z
2 m<4z

so 3z<m<4z from 1 and 2

this in no ways tels us that m+z>0
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Re: GMAT Prep - Need explanations too. [#permalink]  22 Aug 2008, 20:17
stallone wrote:
whats the ans for the 1st DS

i think it shud be E :

1 m>3z
2 m<4z

so 3z<m<4z from 1 and 2

this in no ways tels us that m+z>0

when is 4z > 3z possible?

when z is +ve.
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Re: GMAT Prep - Need explanations too. [#permalink]  24 Aug 2008, 07:30
GMAT TIGER wrote:
PS:
E. A committee of 3 people is to be chosen from 4 married couples. What is the number of different committes that can be chosen if 2 people who are married to each other cannot both serve on the committee?

You can select first memeber of the committee in 8 ways, the second in 6 ways (because we cannot select the spouse of the person already selected) and the 3rd in 4 ways.

There for total ways = 8*6*4

We dont have to calculate the duplicate committees that are formed e.g. A A B , A B A and B A A are the same

So we divide 8*6*4/3!

which gives 32.

HTH
Re: GMAT Prep - Need explanations too.   [#permalink] 24 Aug 2008, 07:30
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