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If Ted brought n baseball cards costs $3 each, then brought twice as

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Math Expert
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If Ted brought n baseball cards costs $3 each, then brought twice as  [#permalink]

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New post 01 Jan 2018, 10:21
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

86% (01:10) correct 14% (01:30) wrong based on 20 sessions

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Re: If Ted brought n baseball cards costs $3 each, then brought twice as  [#permalink]

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New post 01 Jan 2018, 18:08
[(3*N) + (9*2N)] / (3*N)
I got this first equation because there are initially N baseball cards at $3 each, and then twice as many baseball cards (2N) at $9 each. I added those two together to get the total cost that Ted spent buying baseball cards [(3*N) + (9*2N)]. To find the average, I divided that total cost by the number of baseball cards, (3*N,) which I got by adding N + 2N.

Simplifying that equation, I got (21*N)/(3*N)
Cancelling out the two N variables, I got 7 as the final answer (option E).
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Re: If Ted brought n baseball cards costs $3 each, then brought twice as  [#permalink]

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New post 03 Jan 2018, 16:41
Bunuel wrote:
If Ted brought n baseball cards costs $3 each, then brought twice as many cards baseball cards at $9 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to

A. 4n
B. 9
C. 7n
D. 6/n
E. 7

Average cost in dollars = \(\frac{TotalCost}{TotalQty}\)

Total Cost = (Qty\(_1\))(Cost\(_1\)) + (Qty\(_2\))(Cost\(_2\))

(Qty\(_1\))(Cost\(_1\)): \(n\) baseball cards that cost $3 each = n($3)
(Qty\(_2\))(Cost\(_2\)): twice as many cards (as \(n\)) that cost $9 each = 2n($9)

Total Cost in dollars: n(3) + 2n(9)
Total Qty: (n + 2n) = 3n

Average cost in dollars =
\(\frac{n(3) + 2n(9)}{3n}=\frac{3n+18n}{3n}=\frac{21n}{3n}=7\)

Answer E
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If Ted brought n baseball cards costs $3 each, then brought twice as  [#permalink]

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New post Updated on: 03 Jan 2018, 20:53
Turkish similar average problem. Here Avg Cost = Total Cost / Total cards

Sent from my Moto G (5) Plus using GMAT Club Forum mobile app
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Consistency is the Key

Originally posted by laddaboy on 03 Jan 2018, 18:44.
Last edited by laddaboy on 03 Jan 2018, 20:53, edited 1 time in total.
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Re: If Ted brought n baseball cards costs $3 each, then brought twice as  [#permalink]

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New post 03 Jan 2018, 19:52
Bunuel wrote:
If Ted brought n baseball cards costs $3 each, then brought twice as many cards baseball cards at $9 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to

A. 4n
B. 9
C. 7n
D. 6/n
E. 7


Avr cost = (Total cost)/(Number of items)=(3*n+9*2n)/(n+2n)=21n/3n=7
Therefore, E is correct answer
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Re: If Ted brought n baseball cards costs $3 each, then brought twice as   [#permalink] 03 Jan 2018, 19:52
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