GMAT Problem Solving Discussions

tryitnow · June 18, 2009, 7:16am

What is the value of x+7| ?

1. |x+3 = 14
2. (x + 2)^2=169

My answer was C but paper says D. Any idea whats the soln. is?

guy_with_guts · June 18, 2009, 7:33am

What is the value of x+7| ?

1. |x+3 = 14
2. (x + 2)^2=169

My answer was C but paper says D. Any idea whats the soln. is?

1.either x is 11 or -17 , not suffecient
2.x is11,-15
so combining two x is 11
C is the answer.

D can be the answer if its given x is positive.

tryitnow · June 18, 2009, 7:45am

1.either x is 11 or -17 , not suffecient
2.x is11,-15
so combining two x is 11
D is the answer.

C can be the answer if its given x is positive.

Well...D means each statement is sufficient and C means both are needed. That was my point - you need both of these statements.

nuttyvarun · June 18, 2009, 8:06am

What is the value of x+7| ?

1. x+3 = 14
2. (x + 2)^2=169

My answer was C but paper says D. Any idea whats the soln. is?

Option1:
|x+3 = 14, i.e. x can be either -17 or +11
NOT SUFF (No Unique value for x)

Option2:
(x + 2)^2=169, i.e. x can be either -15 or +11
NOT SUFF (No Unique value for x)

taking both together, we get x=11 (common value for x in both eqn).

Thus answer should be option C

BTW... wrong thread!! 😉

aravind1985 · June 18, 2009, 9:04am

I came across this problem. But i am not convinced with the answer.

Please help me sorting the right answer.

How many different four letter words can be formed (the words need not be meaningful) using the letters of the word MEDITERRANEAN such that the first letter is E and the last letter is R?

59
56
23

pearlcrystal · June 18, 2009, 9:54am

Option1:
x+3 = 14, i.e. x can be either -17 or +11
NOT SUFF (No Unique value for x)

Option2:
(x + 2)^2=169, i.e. x can be either -15 or +11
NOT SUFF (No Unique value for x)

taking both together, we get x=11 (common value for x in both eqn).

Thus answer should be option C

BTW... wrong thread!! ;)

It should be D
You don't need to know the value of x to determine x+7|

1) x+7| = |x+3+4| = |x+3 + 4 (since both are positive) = 14 + 4 = 18
2) Take square root of both sides,
==> sqrt {(x+2)^2} = sqrt(169)
==> x+2 = 13
|x+7 can be determined now ...

aniruddha.maiti · June 18, 2009, 10:04am

that's cool, pearl..thanks

guy_with_guts · June 18, 2009, 12:14pm

It should be D
You don't need to know the value of x to determine x+7|

1) x+7| = |x+3+4| = |x+3 + 4 (since both are positive) = 14 + 4 = 18
2) Take square root of both sides,
==> sqrt {(x+2)^2} = sqrt(169)
==> x+2 = 13
|x+7 can be determined now ...

How can u write the quantity in Mod as two diff mod?its possible only when we know X is also positive which is definately not the case here.

try your case with x=-10

guy_with_guts · June 18, 2009, 12:19pm

I came across this problem. But i am not convinced with the answer.

Please help me sorting the right answer.

How many different four letter words can be formed (the words need not be meaningful) using the letters of the word MEDITERRANEAN such that the first letter is E and the last letter is R?

59

56
23

The number of words that can be made from remaining 11 letters is 11 P2=110

we needs to sutract the case

pearlcrystal · June 18, 2009, 12:32pm

How can u write the quantity in Mod as two diff mod?its possible only when we know X is also positive which is definately not the case here.

try your case with x=-10

See ... Thats how you screw up things ...

a+b = |a| + |b iff a, b are positive

a = x+3
b = 4

Given x+3| = 14, so a = 14, but I hurriedly took "a" as positive ... which is not the case ..
My explanation stands cancelled!

friend9921 · June 18, 2009, 7:27pm

Tmay Says
My answer:-2*root(3)

Conservation of TSA=>
TSA=pi*r1*l=1/2*pi*r2^2=>2*r1*l=r2^2=16
=>sqrt(l^2-h^2)*l=8=4x2=>
l=4=>h^2=16-4=>h=2*sqrt2=2*1.414=2.828(approx).

The radius of the circle will form the slant height of the cone.
So, slant height,s =4 units
The semi- circumference of circle will be the circumference of the cone.
Let the radius of the cone be R and that of circle =r.
Then, pi*r=2*pi*R
Since r=4;R=2.
Now we know slant height of cone=sqrt(radius^2+height^2)
=>4=sqrt(2^2+h^2)
=>h=sqrt(12)=2*sqrt(3)

Yes the answer is 2*sqrt(3).

The radius of a semi-circle will form the slant height of the cone??????

nuttyvarun · June 19, 2009, 4:19am

The sequence a1, a2, , a n, is such that an = 2an-1 - x for all positive integers n >= 2 and for certain number x. If a5 = 99 and a3 = 27, what is the value of x?

A. 3B. 9
C. 18
D. 36
E. 45

amar_sinha_25505345 · June 19, 2009, 4:34am

The sequence a1, a2, , a n, is such that an = 2an-1 - x for all positive integers n >= 2 and for certain number x. If a5 = 99 and a3 = 27, what is the value of x?
A. 3B. 9
C. 18
D. 36
E. 45

This is the case of two equation and two variables:
From a5=99
16a1 - 15x =99.................1

From a3 = 27
4a1-3x=27 ....................2
Solving eq1 and eq 2 will give:
x = 3
So A is the answer.

guy_with_guts · June 19, 2009, 4:43am

The sequence a1, a2, , a n, is such that an = 2an-1 - x for all positive integers n >= 2 and for certain number x. If a5 = 99 and a3 = 27, what is the value of x?
A. 3B. 9
C. 18
D. 36
E. 45

represent a5 in terms of a3 and solve.
3 is the answer.

nuttyvarun · June 19, 2009, 5:33am

any short cut method for this one plz..

A certain company that sells only cars and trucks reported that revenues from car sales in 1997 were down 11 percent from 1996 and revenues from truck sales in 1997 were up 7 percent from 1996. If total revenues from car sales and truck sales in 1997 were up 1 percent from 1996, what is the ratio of revenue from car sales in 1996 to revenue from truck sales in 1996?
A. 1 : 2
B. 4 : 5
C. 1 : 1
D. 3 : 2
E. 5 : 3

guy_with_guts · June 19, 2009, 6:40am

any short cut method for this one plz..

A certain company that sells only cars and trucks reported that revenues from car sales in 1997 were down 11 percent from 1996 and revenues from truck sales in 1997 were up 7 percent from 1996. If total revenues from car sales and truck sales in 1997 were up 1 percent from 1996, what is the ratio of revenue from car sales in 1996 to revenue from truck sales in 1996?
A. 1 : 2
B. 4 : 5
C. 1 : 1
D. 3 : 2
E. 5 : 3

I dont thnk short cut is required here as question is simple enough-
let C are the cars in 1996 and T be the trucks in 1996

.89C+1.07T=1.01(C+T)=1.01C+1.01T
12C=6T
C/T=2/1

inanc · June 19, 2009, 9:20am

I need scoretop PS and DS. Would be more than happy if someone can e-mail me @ [email protected]

This thread is for all those junta who will be
appearing for GMAT.....

We dont have a proper GMAT discussion thread. Here I will post post GMAT related problems and discuss them.

Hope to see lots of participants

inanc · June 19, 2009, 9:21am

I need scoretop PS and DS. Would be more than happy if someone can e-mail me @ [email protected]

A jar contains 30 marbles, of which 20 are red and 10 are blue. If 9 of the marbles are removed, how many of the marbles left in the jar are red?

(1) Of the marbles removed, the ratio of the number of red ones to the number of blue ones is 2 : 1.
(2) Of the first 6 marbles removed, 4 are red.

A Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D EACH Statement ALONE is sufficient.
E Statements (1) and (2) TOGETHER are NOT sufficient.

nuttyvarun · June 19, 2009, 1:29pm

I dont thnk short cut is required here as question is simple enough-
let C are the cars in 1996 and T be the trucks in 1996

.89C+1.07T=1.01(C+T)=1.01C+1.01T
12C=6T
C/T=2/1

well.. this in itself is short cut for me, since I was doing some wierdo way..

thanks man!!

BTW.. C/T = 1/2 and not 2/1 😉

nuttyvarun · June 20, 2009, 12:23am

If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?
A. 5 to 4
B. 3 to 2
C. 2 to 1
D. 5 to 1
E. 6 to 1