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A) 25
B) 34
C) 40
D) 46
E) 50

I am getting 46

Thanks,
Sri

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gmattesttaker2 wrote:
Hello,

Mario bought equal numbers of 2 cent and 3 cent stamps. If the total cost of the stamps was $1.00, what was the total number of stamps bought? A) 25 B) 34 C) 40 D) 46 E) 50 Let x = # of 2-cent stamps purchased Since Mario bought equal numbers of 2 cent and 3 cent stamps, we can let x = # of 3-cent stamps purchased So, VALUE (in cents) of the 2-cent stamps purchased = 2x And VALUE (in cents) of the 3-cent stamps purchased = 3x The total cost of the stamps was$1.00
In other words, the total cost was 100 cents

So, we can write 2x + 3x = 100
simplify: 5x = 100
solve: x = 20

So, Mario purchased 20 2-cent stamps and 20 3-cent stamps, for a total of 40 stamps.

Cheers,
Brent

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Brent@GMATPrepNow wrote:
gmattesttaker2 wrote:
Hello,

Mario bought equal numbers of 2 cent and 3 cent stamps. If the total cost of the stamps was $1.00, what was the total number of stamps bought? A) 25 B) 34 C) 40 D) 46 E) 50 Let x = # of 2-cent stamps purchased Since Mario bought equal numbers of 2 cent and 3 cent stamps, we can let x = # of 3-cent stamps purchased So, VALUE (in cents) of the 2-cent stamps purchased = 2x And VALUE (in cents) of the 3-cent stamps purchased = 3x The total cost of the stamps was$1.00
In other words, the total cost was 100 cents

So, we can write 2x + 3x = 100
simplify: 5x = 100
solve: x = 20

So, Mario purchased 20 2-cent stamps and 20 3-cent stamps, for a total of 40 stamps.

Cheers,
Brent
Hello Brent,

Thank you very much for your excellent explanation. I think I overlooked the equal part in the question. Now if this was a data sufficiency question and the question does not mention equal number of 2 cent and 3 cent stamps but asks us to find the total number of stamps, will 41 2-cent stamps and 6 3-cent stamps also be correct since they both add in value to 100 cents? I think I read in one of the postings that if the 2 numbers don't have a common (factor?) then they can have only 1 value. Is this correct? Thanks a lot for your help.

Best Regards,
Sri

Update:

Hello Brent, this was the type of question that I was thinking:

Joanna bought only $0.15 and$0.29 stamps. How many $0.15 stamps did she buy? (1) She bought$4.40 worth of stamps.

This is the post:

Thanks - Sri

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gmattesttaker2 wrote:
Hello Brent,

Now if this was a data sufficiency question and the question does not mention equal number of 2 cent and 3 cent stamps but asks us to find the total number of stamps, will 41 2-cent stamps and 6 3-cent stamps also be correct since they both add in value to 100 cents? I think I read in one of the postings that if the 2 numbers don't have a common (factor?) then they can have only 1 value. Is this correct? Thanks a lot for your help.

Hi Sri,

I'm not aware of any such rule.
Notice that 2 and 3 don't have any common factors, but there are many possible scenarios for the number of stamps that add to $1.00 if we buy 2- and 3-cent stamps only. Here are 3: 20 2-cent stamps and 20 3-cent stamps for a total of 40 stamps 41 2-cent stamps and 6 3-cent stamps for a total of 47 stamps 47 2-cent stamps and 2 3-cent stamps for a total of 49 stamps . . . (there are more) Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! Master | Next Rank: 500 Posts Joined 11 Mar 2009 Posted: 359 messages Followed by: 2 members Upvotes: 50 Target GMAT Score: 900+ gmattesttaker2 wrote: Mario bought equal numbers of 2 cent and 3 cent stamps. If the total cost of the stamps was$1.00, what was the total number of stamps bought?
Let the number of stamps of each type bought be N

Thus N stamps were of 2 cents and N stamps were of 3 cents , making a total of 2N stamps.

So , 2N + 3N = 100

Or, 5N = 100

Or, N = 20

We have taken N as 20 and we know two types of stamps were bought both " N " Numbers .

Thus 20 stamps were of 2 cents and 20 stamps were of 3 cents , making a total of 40 stamps...

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gmattesttaker2 wrote:
I think I read in one of the postings that if the 2 numbers don't have a common (factor?) then they can have only 1 value. Is this correct?
This isn't correct, at least in this context. (It may be in other ones, but not when dealing with equations in two variables.)

Generally speaking, an equation like

2x + 3y = 100

has an infinite number of solutions for x and y.

If you put some restrictions on x and y (such as x and y must both be positive integers), however, you can have a finite number of solutions - sometimes only one (very common in GMAT DS!) But finding that single solution can be a real pain

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

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gmattesttaker2 wrote:
Hello,

Mario bought equal numbers of 2 cent and 3 cent stamps. If the total cost of the stamps was $1.00, what was the total number of stamps bought? A) 25 B) 34 C) 40 D) 46 E) 50 ng x = the number of stamps of each denomination that he bought, we can create the equation: 2x + 3x = 100 5x = 100 x = 20 So x + x = 20 + 20 = 40 stamps were purchased. Answer: C _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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