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Mark bought a set of 6 flower pots...

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fahadmuhammad86
 Post subject: Mark bought a set of 6 flower pots...
 Post Posted: Sat Oct 17, 2009 4:10 pm 
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Students


Posts: 11
Mark bought a set of 6 flower pots of different sizes at a total cost of 8.25. Each pot cost 0.25 more than the next one below in size. What is the cost of the largest pot?

Answer: $2.00

Im just wondering if there is a faster/efficient way of doing this question. Here's my method:

x+(x+0.25)+(x+0.50).......x+1.25=8.25
this will give us cost of the 1st pot.
then x+1.25 will give us the cost of the largest pot= 2

With so many decimals involved, a small miscalculation can lead to the wrong answer. Is there a better way to do this problem ?
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mariabfa
 Post subject: Re: Mark bought a set of 6 flower pots...
 Post Posted: Sat Dec 17, 2011 7:08 pm 
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Students


Posts: 5
did anyone have a response to this one? i am looking for the solution to this same problem
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stud.jatt
 Post subject: Re: Mark bought a set of 6 flower pots...
 Post Posted: Sun Dec 18, 2011 6:27 am 
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Students


Posts: 21
mariabfa wrote:
did anyone have a response to this one? i am looking for the solution to this same problem


use the formula for the sum of an arithmetic series,

Let x be the cost of the smallest pot, then the cost of the largest pot is x + 5*0.25 = x+1.25

now the sum of an arithmetic series can be written as

[(first term + last term)* (number of terms)]/2 = sum

hence
(x + x +1.25)*6/2 = 8.25

or x = 0.75 and the largest pot costs x + 1.25 = 2
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RonPurewal
 Post subject: Re: Mark bought a set of 6 flower pots...
 Post Posted: Tue Dec 27, 2011 5:44 pm 
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ManhattanGMAT Staff


Posts: 7146
fahadmuhammad86 wrote:
With so many decimals involved, a small miscalculation can lead to the wrong answer. Is there a better way to do this problem ?


the best suggestion here is "slow down and check your arithmetic". it really shouldn't be very hard, especially because all of these are numbers that are used every day in common currency calculations (quarters, dollars, etc.)
if you are afraid that you'll make a mistake in a calculation that is this straightforward, then you should probably spend some time practicing your arithmetic, and/or just slow down a little bit when you do the calculations.
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