GMAT Problem Solving Discussions

For a certain race, 3 teams were allowed to enter 3 members each. A team earned
6-n points whenever one of its members finished in nth place, where 1
(A) 0
(B) 1
(C) 2
(D) 3
(E) 4
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150, 200, 250, n

Which of the following could be the median of the 4 integers listed above?

I. 175
II. 215
III. 235


A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III




The second answer would be C ie 175 and 215 only
explanation :
if n if n= 230 then median is 215
but if median has to be 235 then n has to be =

The first answer wud be D

Lets say 2 other teams scored max possible points of 6 each since none scored more than 6 .
total available points = 5+4+3+2+1 =15
there by 3rd team has to win 15-12 = 3pts.
This can also be explained by allotting positions to each team
Hi friends,
See attached an official GMATPrep question. The correct answer is Choice D. However I am not able to work my way to the correct justification. Any help will be most gratefully received.
Many thanks.
- TheToastedBread
Hi friends,
See attached an official GMATPrep question. The correct answer is Choice D. However I am not able to work my way to the correct justification. Any help will be most gratefully received.
Many thanks.
- TheToastedBread

already answered in ds thread
sharkon Says
well then in this case LCM of all nos will be zero . I think we should not take the zero in that set very seriously

Well friends, both answers seem to have valid points. So the million dollar question is which one is correct? ??:
- TheToastedBread
Quote:
Originally Posted by thetoastedbread
Hi All,Perhaps a very fundamental question - In the GMAT world, is 0 (zero) considered to be a multiple of an integer? eg: Would GMAT agree to saying that 0 is a multiple of 5? Or that 0 is a multiple of 6?
- TheToastedBread

Reply Posted by ajayreddy
well..yes....acc. to OG11, any integer y is a multiple of x provided y = xn where n is any integer in the set {...,-3,-2,-1,0,1,2,3,....}


Reply Posted by sharkon
well then in this case LCM of all nos will be zero . I think we should not take the zero in that set very seriously
------------
So, which explanation is correct? ??:
- TheToastedBread

USE ur age old maths common sense . do it as u usually do . Dont consider Zero.



Quote:
Originally Posted by thetoastedbread
Hi All,Perhaps a very fundamental question - In the GMAT world, is 0 (zero) considered to be a multiple of an integer? eg: Would GMAT agree to saying that 0 is a multiple of 5? Or that 0 is a multiple of 6?
- TheToastedBread

Reply Posted by ajayreddy
well..yes....acc. to OG11, any integer y is a multiple of x provided y = xn where n is any integer in the set {...,-3,-2,-1,0,1,2,3,....}


Reply Posted by sharkon
well then in this case LCM of all nos will be zero . I think we should not take the zero in that set very seriously
------------
So, which explanation is correct? ??:
- TheToastedBread

I believe u got the reason for first statement to be enuf.
Data : -2x>3y
looking at the second statement .
2x +5y-20 =0
=> 5y-20 =-2x
=> 5y -20 > 3y (substituting data)
=> 5y-3y> 20
=> y>10

now use this info in data...
=> -2x >30
x is negative

Hence either statement is enuf to answer .




Hi friends,
See attached an official GMATPrep question. The correct answer is Choice D. However I am not able to work my way to the correct justification. Any help will be most gratefully received.
Many thanks.
- TheToastedBread
sharkon Says
USE ur age old maths common sense . do it as u usually do . Dont consider Zero.

i guess sharkon's rite...we wud be better off excluding zero frm the set..

Hi Puys,

I have a few PS queries. These questions r from the Official Guide Quantitative Review...I don't have the answer explantions, only the answer key...
Thanks in advance...
Below r the questions:

191) The inside dimensions of a rectangular wooden box are 6 inches by 8 inches by 10 inches. A cylindrical canister is to be placed inside the box so that it stands upright when the closed box rests on one of the six faces. Of all such canisters that could be used, what is the radius, in inches, of the one that has maximum value?
A) 3 B) 4 C) 5 D) 6 E) 8

196) The ratio, by volume, of soap to alcohol in a certain solution is 2:50:100. The solution will be altered so that the ration of the soap to alcohol is doubled while the ratio of soap to water is halved. If the altered solution will contain 100 cubic centimetres of alcohol, how many cubic centimetres of water will it contain?

a)50 b) 200 c) 400 d) 625 e) 800

220) John and Mary were each paid x dollars in advance to do a certain job together. John worked on the job for 10 hours and Mary worked 2 hours less than John. If Mary gave John y dollars of her payment so that they would have received the same hourly wage, what was the dollar amount, in terms of y, that John was paid in advance?

a)4y b) 5y c) 6y d) 8y e) 9y

234) In a certain game, a large container is filled with red, yellow, green and blue beads worth respectively, 7, 5, 3, 2 points each. A number of beads are then removed from the container. If the product of the point values of the removed beads is 147,000, how many red beads were removed?

a)5 b) 4 c) 3 d) 2 e) 0

23 Right triangle PQR is to be constructed in the xy-plane so that the right angle is at P and PR is parallel to the x-axis. The x- and y- coordinates of P,Q, and R are to be integers that satisfy the inequalities -4
a)110 b) 1100 c) 9900 d) 10000 e) 12100

Answers
Q 191) B
Q 196) E
Q 220) E
Q 234) D
Q 23 A

Hi Puys,

I have a few PS queries. These questions r from the Official Guide Quantitative Review...I don't have the answer explantions, only the answer key...
Thanks in advance...
Below r the questions:

191) The inside dimensions of a rectangular wooden box are 6 inches by 8 inches by 10 inches. A cylindrical canister is to be placed inside the box so that it stands upright when the closed box rests on one of the six faces. Of all such canisters that could be used, what is the radius, in inches, of the one that has maximum value?
A) 3 B) 4 C) 5 D) 6 E) 8

196) The ratio, by volume, of soap to alcohol in a certain solution is 2:50:100. The solution will be altered so that the ration of the soap to alcohol is doubled while the ratio of soap to water is halved. If the altered solution will contain 100 cubic centimetres of alcohol, how many cubic centimetres of water will it contain?

a)50 b) 200 c) 400 d) 625 e) 800

220) John and Mary were each paid x dollars in advance to do a certain job together. John worked on the job for 10 hours and Mary worked 2 hours less than John. If Mary gave John y dollars of her payment so that they would have received the same hourly wage, what was the dollar amount, in terms of y, that John was paid in advance?

a)4y b) 5y c) 6y d) 8y e) 9y

234) In a certain game, a large container is filled with red, yellow, green and blue beads worth respectively, 7, 5, 3, 2 points each. A number of beads are then removed from the container. If the product of the point values of the removed beads is 147,000, how many red beads were removed?

a)5 b) 4 c) 3 d) 2 e) 0

23 Right triangle PQR is to be constructed in the xy-plane so that the right angle is at P and PR is parallel to the x-axis. The x- and y- coordinates of P,Q, and R are to be integers that satisfy the inequalities -4
a)110 b) 1100 c) 9900 d) 10000 e) 12100

Answers
Q 191) B
Q 196) E
Q 220) E
Q 234) D
Q 23 A

191.
consider the cuboid...u hv three diff. rectangles - 6x8, 8x10 and 6x10 tht form the faces of the cuboid...if the cylinder rests on the 6x8 rectangle, then the max. diameter it can hv is 6 inches and max. height is 10 inches..hence volume = 90pi
when u consider 8x10 face, max dia = 8 in. and max vol = 96pi
when u consider 6x10 face, max dia = 6 in. and max vol = 72pi
hence, max vol = 96pi when dia = 8 in. i.e. radius = 4 inches

196.
missing data - ratio of soap:alcohol:water = 2:50:100

whenever a ratio is doubled or halved, u double or halve the first quantity of the ratio.
hence, soap:alcohol = 4:50
soap:water = 1:100
since it contains 100 cc of alcohol, amt. of soap = 8 cc. hence amt. of water = 800 cc.

220.

both were given x dollars in advance. let us assume their hourly wage be 'a' dollars.
thus, if john worked for 10 hrs, he shud get 10a dollars and mary shud get 8a dollars.
now, mary gave y dollars to john. hence, amt. left with mary = x-y. this is equal to the total wage tht she gets
therefore x-y = 8a
john gets x+y dollars. thus x+y = 10a
solving both the equations, u get x=9y.

234.

since we need to find only how many red beans were removed, we need to find hw many times 7 occurs as a factor of 147000...
147 = 49x3 = 7x7x3
thus, there were 2 red beans removed.

23_.

consider pt.P.. within the range -4 to 5 for x co-ordinate, it can have 10 values...similarly, for y co-ordinate, it can have values frm 6 to 16 i.e. 11 values...thus a total of 110 possible co-ordinate values.
now, R will hv the same y co-ordinate as P...hence, y co-ordinate of R can have 9 values (1 value is already assigned to P amongst the original 10 values)
similarly, Q will hv same X co-ordinate.hence, Q can have 10 values for x co-ordinate.
thus, total no. of triangles = 110 x 9 x 10 = 9900...i think this is the right answer and not 110...plz tell me if i am right or wrong...
if x^2 + 5y = 49, is y an integer?
(1) 1 (2) x^2 is an integer.

EXPLANATION:
You can rearrange the equation to read

5y = 49 - x^2, or y = (49-x^2)/5. y will be an integer if 49-x^2 is a multiple of 5.
Statement 1 tells you that x is greater than 1, but less than 4. so 1 Statement 2 tells you that x^2 is an integer, which means 49-x^2 is an integer, but does not tell you if it is a multiple of 5. Eliminate answer (2).
combining the statements gives you that x^2 is an integer between 1 and 16. This still does not help, since 49-x^2 could be a multiple of 5, say x^2=2, or may not be a multiple of 5, say if x^2=1.

Hey!!

Would appreciate if I get an explanation to the following question's explanation from KAPLAN

Also I have a few more doubts attached. Please help me resolve them ASAP as I have my exam in 3 days.

Thanks in Advance

Also I have a few more doubts attached. Please help me resolve them ASAP as I have my exam in 3 days.

Thanks in Advance

i think for the first question, u can choose 2 lightbulbs from a lot of 12 in 12C2 = 66 ways and not 72 ways....

the answer to the second question is 1/4th and nt 1/6th....this answer can be easily solved by using each option and then checking if 3 x amt. saved = amt. not saved.
if she saved 1/4th of her income each month and assuming her income to be 1 each month, then at the end of the year, she wud hv saved 12 x 1/4 = "3"....hence, the amt. not saved = 12 - 3 = 9 which is three times the amt. she saved....

for the third problem, the mean is 8.1 with a s.d. of .3 thus the acceptable range is 7.8 - 8.4...amongst the data of 12 cups given above, only 9 satisfy this condition...thus the answer is 9.

Hey Ajay,

Thanks for the response. Here are a few more ...
Apart from the oe attached please clarify if the below steps have any mistake:
x(x - 1) = x
=>x - 1 = 1
=>x = 2

Hey Ajay,

Thanks for the response. Here are a few more ...
Apart from the oe attached please clarify if the below steps have any mistake:
x(x - 1) = x
=>x - 1 = 1
=>x = 2

see, for the problem u hv written, u need to first open the brackets since 'x' is a variable and it can have more than one values....
hence,
x^2-x = x
x^2-2x = 0
x(x-2) = 0
x = 0 or x = 2...thus u see, u can hv two possible values


as far as ur attached document problem goes, i can at present think of the foll. solution only:

when n = 4, h(n)+1 = 9....thus prime factor = 3
when n = 6, h(n)+1 = 49....thus prime factor = 7
when n = 10, h(n)+1 = 3841...thus prime factor = 23
so u can see, the smallest prime factor keeps on increasing as the value of 'n' increases...thus we can safely assume that the smallest prime factor for h(100)+1 will be greater than 40

Thanks again.

Now the questions seem fairly simple. But While attempting the exam....

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Hi guys
Can someone please help me with DS problem :-
Both the ranges of 2 lists are from 1 to 100, whose deviation is greater?
1) List 1 has three 100 and two 50; List 2 has two 100 and three 50.
2) The averages are the same.
Also, can someone please explain the relation between range and SD... I mean how to go about comparing SD when range is given for two series ??
Hi guys
Can someone please help me with DS problem :-
Both the ranges of 2 lists are from 1 to 100, whose deviation is greater?
1) List 1 has three 100 and two 50; List 2 has two 100 and three 50.
2) The averages are the same.
Also, can someone please explain the relation between range and SD... I mean how to go about comparing SD when range is given for two series ??

see, acc. to me, i feel that neither of the statements is sufficient by itself to give a unique answer...however, when u combine both the statements, then u come to a solution:

we know the range for both the sets is 1-100....using statement 2, we know that the average of both the lists is same...the deviation is defined as
((Xavg - X)/n)
since the average of both the lists is same and since list 1 has three 100's, the s.d. of list 1 wud obviously be greater than s.d. of list 2
hence, acc. to me, the answer is C...is it right?
Thanks again.

Now the questions seem fairly simple. But While attempting the exam....

well, its all a matter of nerves..if u can keep ur cool and TRY to think u r solving OG questions, i think u ll be able to crack it...c...all depends on u on the D-day...best of luck neways..