GMAT Problem Solving Discussions

MBA
4126
The product of the units digit, the tens digit, and the
hundreds digit of the positive integer m is 96. What is
the units digit of m ?
(1) m is odd.
(2) The hundreds digit of m is 8.


Factorization problem:
The prime factors of 96 = 2*2*2*2*2*3 (Remember digits have to be single)
from stmt 1: m is odd. The only odd digit possible in the units place is 3. Hence m=3(sufficient)
from stmt 2: if hundreds digit is 8 then units digit of m can be 2,4,6,3... (Insufficient)

Hence answer choice was (A)
4127

Q7 PS in OG11. I am not able to understand the answer...can somebody help?

Thanks in advance.

It is very hard to draw a diagram (I tried hard) here...but it is X Y coordinate plane with an oval kind of shape touching X and Y base.

Question is

On the graph above, when x=1/2, y = 2; and when x =1 and y =1. The graph is symmertrical with respect to the vertical line at x=2. According to the graph, when x=3, y =?

Answer is = 1. Since the paragraph is symmetric with respect to x=2, the y value when x=3 will be the same as they y value when x=1, which is 1.

I am not able to understand the concept..

4128

Factorization problem:
The prime factors of 96 = 2*2*2*2*2*3 (Remember digits have to be single)
from stmt 1: m is odd. The only odd number possible is 3. Hence m=3(sufficient)
from stmt 2: if hundreds digit is 8 then m can be 2,4,6 (Insufficient)

Hence answer choice was (A)

Boss when it is written m is odd means abc is odd number and factors of 96 are 2^5*3 which is odd*even is even. can u elaborate pls.they have not written unit digit is odd.pls explain the concept.
4129
245857anu Says
Boss when it is written m is odd means abc is odd number and factors of 96 are 2^5*3 which is odd*even is even. can u elaborate pls.they have not written unit digit is odd.pls explain the concept.


The number m = a b c will ONLY be odd number when the units digit of m is odd. Since 3 is required to make the products of the digits 96, the units digit will have to be 3
4130
euros Says
The number m = a b c will ONLY be odd number when the units digit of m is odd. Since 3 is required to make the products of the digits 96, the units digit will have to be 3


got your pooint thanx.c
can u pls tell me why x^2-4| is positive or >0 why not negative.

What is the value of y?

(1) 3|x^2 - = y - 2

(2) 3 - = 11
OA and explaination.
4131
The product of the units digit, the tens digit, and the
hundreds digit of the positive integer m is 96. What is
the units digit of m ?
(1) m is odd.
(2) The hundreds digit of m is 8.


When 96 is factorised we get 3*4*8.We need to find which is the unit digit among the 3 nos.

Statement 1: m is odd...There is only one odd no in the above factorisation.So unit digit has to be 3 to make m odd. Sufficient.

Statement 2: no use.Cannot find the unit digit from this.

So I will go with option A

-Deepak.
4132

Hi,
I recently took the GMAT and got a question that I wasn't sure of how to answer. I hope one of you can solve this for me in steps:

2008^2008 - 2008^2007 = 2007^x

what is the value of x?

Options were like: 0, 1, 2007, 2008, 2006, etc

4133
Hi,
I recently took the GMAT and got a question that I wasn't sure of how to answer. I hope one of you can solve this for me in steps:

2008^2008 - 2008^2007 = 2007^x

what is the value of x?

Options were like: 0, 1, 2007, 2008, 2006, etc


Have you posted the complete q? Solving I get

2008^2007 * 2007 = 2007 ^x .

On comparing the 2007 bases ,I get x = 1 . I'm not sure abt this

-Deepak.
4134
A challenging probability question which came to my mind...

Q) If a man climbs a staircase having 12 steps by jumping one step, two steps or three steps at a time in any order. What is the probability that he took at least two three step jumps?


Nice sum. what are the options...
4135
Have you posted the complete q? Solving I get

2008^2007 * 2007 = 2007 ^x .

On comparing the 2007 bases ,I get x = 1 . I'm not sure abt this

-Deepak.



Ya I posted the complete question.
how do u get to that? i asked someone else about this who explained it this way:
2008^2008-2008^2007 comes to 2008 by way of this formula: a^m - a^n = a^m-n. so that means 2008 = 2007^x. Is that how its to be done?
4136
Ya I posted the complete question.
how do u get to that? i asked someone else about this who explained it this way:
2008^2008-2008^2007 comes to 2008 by way of this formula: a^m - a^n = a^m-n. so that means 2008 = 2007^x. Is that how its to be done?


I'm sure this formula is not correct. a^m - a^n is NEVER EQUAL to a^(m-n)

a^m / a^n = a^(m-n) .

Simply substitution will tell

2^3 - 2^2 = 8-4 = 4

By your formula : 2^3 - 2^2 = 2^(3-2) = 2^1 = 2

So I think there must be some other method that I'm not aware of to solve this problem.


-Deepak.
4137

Factorization problem:
The prime factors of 96 = 2*2*2*2*2*3 (Remember digits have to be single)
from stmt 1: m is odd. The only odd digit possible in the units place is 3. Hence m=3(sufficient)
from stmt 2: if hundreds digit is 8 then units digit of m can be 2,4,6,3... (Insufficient)

Hence answer choice was (A)

245857anu Says
Boss when it is written m is odd means abc is odd number and factors of 96 are 2^5*3 which is odd*even is even. can u elaborate pls.they have not written unit digit is odd.pls explain the concept.

euros Says
The number m = a b c will ONLY be odd number when the units digit of m is odd. Since 3 is required to make the products of the digits 96, the units digit will have to be 3

@245857anu, There was slight misinterpretation at my end. @euros is correct. The answer choice however remains the same. I have modified the explanation. I actually read this "What is
the units digit m" so for me m was the units digit, but fortunately this question can be done with the misinterpreted form ...But can't always get lucky :shocked:....so I will be more careful the next time.
4138
Hi,
I recently took the GMAT and got a question that I wasn't sure of how to answer. I hope one of you can solve this for me in steps:

2008^2008 - 2008^2007 = 2007^x

what is the value of x?

Options were like: 0, 1, 2007, 2008, 2006, etc

Let me this say first, I don't see this as a correct Question.
Here is a proposed solution.
2008^2007(2008-1) = (2008^2007)*2007
=> (2007+1)^2007 = 2007^(x-1)
Using LOG base 10, 2007 log (2007 + 1) ~ 2007 log 2007
2007*log 2007 = (x-1) log 2007
Hence x-1 = 2007 , so x=2008 (Ans)
4139
Here is GMAT Prep question. Please post your explanation.
4140
GMAT QUESTION:
2008^2008 - 2008^2007 = 2007^x
2008^7(2008-1)=2007^x
(2007)=2007^x
x=1
4141
GMAT QUESTION:
2008^2008 - 2008^2007 = 2007^x
2008^7(2008-1)=2007^x
(2007)=2007^x
x=1

I believe you meant 2008^2007(2008-1)=2007^x in the second line.
4142
Gail.Wynand Says
Here is GMAT Prep question. Please post your explanation.

Answer: 1/5 [She saved 20% of her take home pay]

Suppose S is the amount saved each month and P is the take home pay per month

So, lets us say that S = P / X

Also Saving for one year = 12. S

As per the problem
12.S = 3 [ P - S]

But we know that P = S.X
12.S = 3 [ S.X - S]

Solving you get X = 5
4143
Gail.Wynand Says
Here is GMAT Prep question. Please post your explanation.


Suppose the per month salary is 100. Saving is x.

Per month spending is 100 - x [ 12 (100 -x) for 1 year].

Yearly spending = 3 times of yearly saving

1200 -12x = 3 * 12x

x = 1200 / 48

x = 25 rs out of 100. Therefore saving is 1/4.
4144
Gail.Wynand Says
Here is GMAT Prep question. Please post your explanation.


Here is huv I worked it out

Salary = salary per month
Save = savings per month


save*12 = 3*(salary-save)

12save = 3salary - 3save

15save = 3salary

save = salary/5

-Deepak.
4145
Answer: 1/5 [She saved 20% of her take home pay]

Suppose S is the amount saved each month and P is the take home pay per month

So, lets us say that S = P / X

Also Saving for one year = 12. S

As per the problem
12.S = 3 [ P - S]

But we know that P = S.X
12.S = 3 [ S.X - S]

Solving you get X = 5

Suppose the per month salary is 100. Saving is x.

Per month spending is 100 - x [ 12 (100 -x) for 1 year].

Yearly spending = 3 times of yearly saving

1200 -12x = 3 * 12x

x = 1200 / 48

x = 25 rs out of 100. Therefore saving is 1/4.

Here is huv I worked it out

Salary = salary per month
Save = savings per month


save*12 = 3*(salary-save)

12save = 3salary - 3save

15save = 3salary

save = salary/5

-Deepak.

I guess I misinterpreted the question.

Deepakram & earnestpromises, you got it.

Just that DeepakRam's approach is relatively simple and straight forward in my opinion.