GMAT Problem Solving Discussions

answer is 5.6 days.
so my take is 6 days


your calculation is correct.... this is what probably you've done

Total man-days needed = 10 X 110 = 1100
Man-days worked before 61st day =(60-5)X10 = 550
Man-days worked after 61st day = 16 X (40-x), where x is the number of days it rained after day 60.
1100 = 550 + 16(40-x)
16x = 90 ---> x = 5.6....

now here is the trick part ..... if it rained for exactly 5.6 days .... the job was completed in 100 days ... if you answer 6, the it'll take 0.4 more days to complete the job ... so the right answer is 5 days ... option B
the answer is B... you were close... all the values of X are in set (-1,0) U (1, infinite) and for all these values ... X > -1 will always be true...

if we select A, then we are leaving negative values of X..

Remember, the question is not asking all the possible values of X .. the question is "which of the following must be true for all X" ...

Only option B will always be true for all X



My answer is A. All the value of X should satisfy the equation given.

Here is my explanation as to why B is not my answer.

If we take X = 0.1, then the condition fails so we cannot say that X> -1
My answer is A. All the value of X should satisfy the equation given.

Here is my explanation as to why B is not my answer.

If we take X = 0.1, then the condition fails so we cannot say that X> -1


you can not take X = 0.1, because X is already defined in the first line. If X/X
this is the definition of X, this the universe where we have to find a condition that is true for all values of X in this universe...
you can not take X = 0.1, because X is already defined in the first line. If X/X
this is the definition of X, this the universe where we have to find a condition that is true for all values of X in this universe...


Exactly. If one of the value from my set does not satisfy the equation, that is not my answer.

Whatever value I pick from the set, it should satisfy the equation and only then, we are right in choosing the set.

For e.g.

Lets say x> 5

Possible of set of X = {4,5,6}

Here only 6 satisfies the equation so this possible set is wrong.
If X/X|
X>1

X>-1

X
X = 1

X^2 > 1


yes ...even i agree with others ...Ans is A

For must be type questions, its like for any and every given value of x the condition must be satisfied ....

so, if u say ans is B ...for every real value of x greater than -1, X/X -1 is not valid)

its not the other way round, as in for any value that satisfies X/|X
correct way to interpret is "what should be the domain of x , such that the condition is met" there could be a few values outside the domain which may satisfy the given condition, but u cannot generlize and include in the domain ...

For must be question its better to refute 4 incorrect options to get the correct answer ...
If X/X|
X>1

X>-1

X
X = 1

|X^2 > 1


I am taking a few examples to solve this one;
Let X/X = Y
now if,
X = -(0.5), then Y = -1, X > Y
X = -(2), then Y = -1, Y > X
X = -(0.9), then Y = -1, X > Y
X = 10, then Y = 1, X > Y

My Answer is option B i.e. X>-1 :)
I am taking a few examples to solve this one;
Let X/X = Y
now if,
X = -(0.5), then Y = -1, X > Y
X = -(2), then Y = -1, Y > X
X = -(0.9), then Y = -1, X > Y
X = 10, then Y = 1, X > Y

My Answer is option B i.e. X>-1 :)


Ok ...in ur eg we need to confirm that for any value of X>-1 , X>Y
If,
X = 0.5, then Y = 1, X

Hi Guys,

Can any body please solve the below problem:

In a certain game, a large container is filled with red, yellow, green, and blue beads worth, respectively, 7, 5, 3, and 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

Hi Guys,

Can any body please solve the below problem:

In a certain game, a large container is filled with red, yellow, green, and blue beads worth, respectively, 7, 5, 3, and 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



Put 147000 in the form of 2,3,5,7

147000 = 5^3 * 2^3 * 7^2 * 3 (Note: 5 cube * 2 cube = 1000)

Hence the ans is D.
Hi Guys,

Can any body please solve the below problem:

In a certain game, a large container is filled with red, yellow, green, and blue beads worth, respectively, 7, 5, 3, and 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


Answer: D

14700= 3*7*7*1000

so 2 Red beads were removed.
Ok ...in ur eg we need to confirm that for any value of X>-1 , X>Y
If,
X = 0.5, then Y = 1, X

Answer is B ... its a classic GMAT question .. not very tough ... but the answer choices makes it tricky .. these type of question take you from 49 to 51 ....

Allow me to explain ... Please take a step back and try to understand

you are trying to answer a different question ....

the question asked is "If X/X|

while you are answering "For which of the following conditions of X, X/X

If you still can't get it ... consider this question ....
Y is a member of set S =
which of the following must be true for all Y
A. Y >= 4
B. Y >= -4
here B is the answer ....


now compare it with our original question
if X/|X
you can not take X = 0.5 because its not define as X ....

In our question first X is defined, then its asking that which of the following will always be true for all X .... it doesnt say that reveres is also must be true

Thanks guys..
I did not get the meaning og "Produc of the point values" and hence i was multiplying with pount and numbe rof bead- rather i should multiplt on points of each beads..

thanks again..

I have this very simple and commonly asked question from Probability here.. I just wanted to understand the quickest way to derive the answer..

If there are two brothers in a group of 5 boys and these boys are lined up at random, what is the probability that the brothers will be next to each other?

Share you thoughts please =)

I have this very simple and commonly asked question from Probability here.. I just wanted to understand the quickest way to derive the answer..

If there are two brothers in a group of 5 boys and these boys are lined up at random, what is the probability that the brothers will be next to each other?

Share you thoughts please =)


5 boys can be arranged in 5! ways ...
consider 2 brothers as a single unit ...hence remaining 3 boys and this single units together make 4 units ...
and 2 brothers can themselves be arranged in 2 ! ways ...

Hence, total no of ways such that 2 boys are always together = 4!*2!

Hence, probability that 2 boys are always together = 4!*2!/5! = 2/5

i guess this should be the fastest way ...

Guys..I found a question in one of the simulated tests. It follows.

Two intersecting lines form four angles. Are the lines perpendicular?

(1) Each of the angles is equal to exactly one of the other three angles.

(2) The sum of three angles does NOT equal to 270 degrees.

A) Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.

B) Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.

C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.

D) Either statement BY ITSELF is sufficient to answer the question.

E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, meaning that further information would be needed to answer the question.


Now I think the answer is B because (1) is nothing but a restatement of the property of intersection of two straight lines. It is always true. But the answer in the test says that it should be D.

What should be the correct answer?

Guys..I found a question in one of the simulated tests. It follows.

Two intersecting lines form four angles. Are the lines perpendicular?
(1) Each of the angles is equal to exactly one of the other three angles.
(2) The sum of three angles does NOT equal to 270 degrees.
A) Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
B) Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
D) Either statement BY ITSELF is sufficient to answer the question.
E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, meaning that further information would be needed to answer the question.

Now I think the answer is B because (1) is nothing but a restatement of the property of intersection of two straight lines. It is always true. But the answer in the test says that it should be D.

What should be the correct answer?


2 things here..

#1. IMPORTANT: there is a separate thread for DS queries >> http://www.pagalguy.com/discussions/gmat-data-sufficiency-discussions-25020702

Please post your DS queries in there.

#2. the answer is option D.
Statement 1 says;
"Each of the angles is equal to exactly one of the other three angles". This means all 4 are not same, i.e. all 4 are not 90 deg. Which answers the question fine.

Statement 2 says;
"The sum of three angles does NOT equal to 270 degrees"
This is self explanatory I believe... the sum of any 3 angles should be 270 deg for it to be perpendicular set of lines.

Have fun!!
Guys..I found a question in one of the simulated tests. It follows.

Two intersecting lines form four angles. Are the lines perpendicular?
(1) Each of the angles is equal to exactly one of the other three angles.
(2) The sum of three angles does NOT equal to 270 degrees.
A) Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
B) Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
D) Either statement BY ITSELF is sufficient to answer the question.
E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, meaning that further information would be needed to answer the question.

Now I think the answer is B because (1) is nothing but a restatement of the property of intersection of two straight lines. It is always true. But the answer in the test says that it should be D.

What should be the correct answer?


yes, ans is indeed D ...

indeed, statement 1 is nothing but implied property of intersecting lines ..
but, each of the angle is equal to exactly one of the 3 other angles...i.e one pair is definitely acute and the other is definitely obtuse ...if lines wud have been perpendicular... each of the angles would have been equal to all the 3 angles...violation of statement 1 ...hence lines are definitely not perpendicular ...sufficient ......Ans D .

trick was to read between the lines πŸ˜ƒ

Thanks for the quick reply and for letting me know about the other forum. I missed that 'exactly one' part 😞

70 students are enrolled in Math, English or German. 40 students are in Math, 35 in English and 30 in German. 15 students are enrolled in all three of the courses. How many students are enrolled in exactly two of the courses: Math, English and German?

A. 10 B. 5 C. 15 D. 25 E. Cannot be determined


I have been having problems with these count problems. Please provide a complete explanation on how you arrived at the answer.

Thanks.

Vikram,

Here is the solution:

Tr.y to do it by set theory.
let x = no of student in math and german,
y = no of student in math and eng
z = no of student in eng and german

so total student in only in math = 40 - (x +y + 15 )
similarly only in eng = 35- (z +y + 15 ) and
only in german = 30 - (x +z + 15 ).

now, 40 - (x +y + 15 ) + 35- (z +y + 15 ) + 30 - (x +z + 15 ) + (x +y+z + 15 ) = 70

which gives x + y + z = 5 = no of student in exactly two of the cources.

Sujoy