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09 Jan 2018, 23:48
00:00

Difficulty:

35% (medium)

Question Stats:

72% (02:02) correct 28% (02:50) wrong based on 37 sessions

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If Ted bought n baseball cards that cost $4 each, then bought twice as many baseball cards at$7 each, and n-2 cards at $6 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to A. 6 B. (6n - 3)/n C. (6n - 6)/(2n - 1) D. 12n/(2n - 1) E. 17/3 _________________ Intern Joined: 15 Aug 2017 Posts: 12 Re: If Ted bought n baseball cards that cost$4 each, then bought twice as  [#permalink]

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10 Jan 2018, 01:28
3
n no of cards each $4 cost=4n 2n no of cards each$7 cost=7X2n=14n
n-2 no of cards each$6 cost=6X(n-2)=6n-12 Mean cost= (4n+14n+6n-12)/(n+2n+n-2) =6 So A examPAL Representative Joined: 07 Dec 2017 Posts: 1153 Re: If Ted bought n baseball cards that cost$4 each, then bought twice as  [#permalink]

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10 Jan 2018, 03:26
1
Bunuel wrote:
If Ted bought n baseball cards that cost $4 each, then bought twice as many baseball cards at$7 each, and n-2 cards at $6 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to A. 6 B. (6n - 3)/n C. (6n - 6)/(2n - 1) D. 12n/(2n - 1) E. 17/3 Since we have variables in our question and answer, we'll pick easy numbers to work with. This is an Alternative approach. Let's say that n = 2. Then Ted bought 2 cards at$4 and 4 cards at $7 giving an average of 8+28/6 =$6 per card.
(A) could be correct, let's check the others.
(B) is 33/6 which is not 6. No!
(C) is 30/11 which is not 6. No!
(D) is 72/11 which is not 6. No!
(E) is 17/3 which is not 6. No!

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Re: If Ted bought n baseball cards that cost $4 each, then bought twice as [#permalink] ### Show Tags 10 Jan 2018, 08:37 Bunuel wrote: If Ted bought n baseball cards that cost$4 each, then bought twice as many baseball cards at $7 each, and n-2 cards at$6 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to

A. 6
B. (6n - 3)/n
C. (6n - 6)/(2n - 1)
D. 12n/(2n - 1)
E. 17/3

$$\frac{4n + 14n +6n - 12}{(n + 2n + n - 2)}$$

= $$\frac{24n - 12}{4n - 2}$$

= $$6$$ , Answer must be (A)
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16 Jan 2018, 17:45
Bunuel wrote:
If Ted bought n baseball cards that cost $4 each, then bought twice as many baseball cards at$7 each, and n-2 cards at $6 each, then the average (arithmetic mean) cost, in dollars per baseball card, is equal to A. 6 B. (6n - 3)/n C. (6n - 6)/(2n - 1) D. 12n/(2n - 1) E. 17/3 We are given that the number of 4-dollar cards = n, the number of 7-dollar cards is 2n, and the number of 6-dollar cards = n - 2. Using the formula: average = sum/number we have: [4n + 7(2n) + 6(n-2)]/(n + 2n + n-2) = average (4n + 14n + 6n - 12)/(4n - 2) = average (24n - 12)/(4n - 2) = average 6(4n - 2)/(4n - 2) = 6 Answer: A _________________ # Scott Woodbury-Stewart Founder and CEO Scott@TargetTestPrep.com 122 Reviews 5-star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button. Re: If Ted bought n baseball cards that cost$4 each, then bought twice as   [#permalink] 16 Jan 2018, 17:45
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