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# At a certain theater, the cost of each adult's ticket is $5 and cost SORT BY: Tags: Show Tags Hide Tags Intern Joined: 30 Jun 2008 Posts: 4 Own Kudos [?]: 114 [43] Given Kudos: 0 Director Joined: 07 Nov 2007 Posts: 717 Own Kudos [?]: 3085 [1] Given Kudos: 5 Location: New York Intern Joined: 17 Dec 2009 Posts: 12 Own Kudos [?]: 9 [0] Given Kudos: 0 Intern Joined: 10 Nov 2009 Posts: 2 Own Kudos [?]: 2 [0] Given Kudos: 1 Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
But the ratio provided by A doesn't hold true if you use different values: let's say that 120 children tickets were sold and 80 adults tickets were sold (same ratio as 3 to 2) then we have:

5(120)+2(80)/200 and the average price is not the same.

I choose C for this for that reason. I know it's wrong but can someone explain. Thanks.

adamsith2010 - I think the ratio does hold true if you use other values. There is an error in your equation. If we use the 120 children tickets and 80 adult like you mentioned the equation looks as follows:

5(80)+2(120)/200 =====> 640/200 = 3.2 same average as if we used the original ration.

I hope this helps
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Re: At a certain theater, the cost of each adult's ticket is $5 and cost [#permalink] 1 Kudos If you take a conceptual approach to this problem, the ratio is all you need to get weighted average of the sold tickets. X= the number of adult tickets sold Y=number of the children ticket sold Average = (5*X+2*Y)/(X+Y) As you have a ratio of Y/X, you can express Y in terms of X (or vise versa). As a result Average expression will become independent of X and Y. A is sufficient obviously Originally posted by alexBLR on 08 Feb 2010, 15:23. Last edited by alexBLR on 08 Feb 2010, 20:07, edited 1 time in total. Intern Joined: 22 Jan 2010 Posts: 1 Own Kudos [?]: [0] Given Kudos: 0 Concentration: Finance, General Management Schools:Wharton GPA: 3.15 Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
prashi82 wrote:
Que:- At a certain theater, the cost of each adult's ticket is $5 and cost of each child's ticked is$2. What was the average (arithmetic mean) cost of all adult's and children's tickets sold at the theater yesterday.

a) Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2.

b) Yesterday 80 adult's tickets were sold at the theater.

Can someone help me with this one?

Thanks
Prashi82

(5x+2y)/(x+y) is the average. However from 1) we know that x/y = 3/2 ie 2x = 3y. use this to solve for first equation which will be 3.2 Hence Sufficent
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Re: At a certain theater, the cost of each adult's ticket is $5 and cost [#permalink] I picked A because it gave the same average cost per ticket for different numbers i picked. algebrically when you form the equation it is like : ( 5x+2y ) / x+y , ST 1 says that y = 3/2x , when you substitute you get one value which is 16/5 or 3.2 GMAT Club Legend Joined: 19 Dec 2014 Status:GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Posts: 21835 Own Kudos [?]: 11790 [2] Given Kudos: 450 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
2
Kudos
Hi All,

When you're dealing with "ratio data" in a DS question, it's actually really easy to prove if a pattern exists or not - just run through a few quick TESTs...

Here, we're told:
Adult tickets cost $5 each Children's tickets cost$2 each

We're asked for the AVERAGE COST of all tickets sold yesterday.

Fact 1: The ratio of Children's tickets to Adult's tickets was 3:2 yesterday.

Some Test Takers can clearly see that this ratio IS enough information to say that Fact 1 is SUFFICIENT. Here's how you can quickly prove the consistency...

IF...
3 children
3(2) + 2(5) = 16/5 = $3.20 average ticket price 6 children 4 adults 6(2) + 4(5) = 32/10 =$3.20 average ticket price

9 children
9(2) + 6(5) = 48/15 = $3.20 average ticket price With this ratio, the average is ALWAYS$3.20
Fact 1 is SUFFICIENT

Fact 2: 80 Adult tickets were sold

Here, we don't know the number of Children's tickets, so the average ticket price would change depending on THAT number. Again, here's the proof:

0 children
0 + 80(5) = 400/80 = $5 average ticket price 80 children 80 adults 80(2) + 80(5) = 560/160 =$3.50 average ticket price
Fact 2 is INSUFFICIENT

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Re: At a certain theater, the cost of each adult's ticket is $5 and cost [#permalink] 1 Kudos 1 Bookmarks Expert Reply At a certain theater, the cost of each adult's ticket is$5 and the cost of each child's ticket is $2. What was the average cost of all the adult's and children's tickets sold at the theater yesterday? The average cost = (2*C+5*A)/(C+A) (1) Yesterday ratio of # of children's ticket sold to the # of adult's tickets sold was 3 to 2 --> 3A =2CA = 2C/3 --> the average cost = C(2+5*2/3)/(C(1+2/3)) --> (2+5*2/3)/(1+2/3). Sufficient. (2) Yesterday 80 adult's tickets were sold at the theater --> A = 80. We know nothing about C. Not sufficient. Answer: A Intern Joined: 21 Dec 2015 Posts: 16 Own Kudos [?]: 23 [0] Given Kudos: 29 WE:Account Management (Commercial Banking) Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
This is a double Matrix Question :

We know Adult price is $5 and Child Price is$2.

Option A:

The ratio of C:A is 3:2

Number Price Total
Child 3x 2 6x
Total 5x 16x

Average can be found as we have the total and individual components.

Option B: Individual component of Adult number of tickets are given, giving no clue to the number of tickets sold for the children.

Hope it helps.
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Re: At a certain theater, the cost of each adult's ticket is $5 and cost [#permalink] 1 Kudos 2 Bookmarks Expert Reply prashi82 wrote: At a certain theater, the cost of each adult's ticket is$5 and cost of each child's ticked is $2. What was the average (arithmetic mean) cost of all adult's and children's tickets sold at the theater yesterday. (1) Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2. (2) Yesterday 80 adult's tickets were sold at the theater. We are given that the cost of each adult's ticket is$5 and cost of each child's ticket is $2. We need to determine the average (arithmetic mean) cost of all adults’ and children's tickets sold at the theater yesterday. If we let a = the number of adults’ tickets sold and c = the number of children’s tickets sold, we can create the following average equation: Average = (5a + 2c)/(a + c) Statement One Alone: Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2. Using the information in statement one, we can create the following equation: c/a = 3/2 2c = 3a c = 1.5a Since c = 1.5a, we can substitute 1.5a for c in our average equation and we have: Average = (5a + 2 x 1.5a)/(a + 1.5a) Average = (5a + 3a)/2.5a Average = 8a/2.5a Average = 3.2 Statement one alone is sufficient to answer the question. We can eliminate answer choices B, C, and E. Statement Two Alone: Yesterday 80 adult's tickets were sold at the theater. Only knowing the number of adults’ tickets sold yesterday is not enough information to determine the average cost of all tickets sold. Statement two alone is not sufficient to answer the question. Answer: A Intern Joined: 23 Apr 2014 Posts: 44 Own Kudos [?]: 24 [0] Given Kudos: 82 Location: United States GMAT 1: 680 Q50 V31 GPA: 2.75 Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
prashi82 wrote:
At a certain theater, the cost of each adult's ticket is $5 and cost of each child's ticked is$2. What was the average (arithmetic mean) cost of all adult's and children's tickets sold at the theater yesterday.

(1) Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2.

(2) Yesterday 80 adult's tickets were sold at the theater.

Statement 1 - let number of children's ticket and adult's ticket sold = 3x and 2x
So average cost = (2x *5 + 3x*2)/3x+2x
= 16x/5x = 16/5 ----sufficient

Statement 2 - Number of adult tickets sold = 80 but no info about number of children's ticket. --not sufficient.

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Re: At a certain theater, the cost of each adult's ticket is $5 and cost [#permalink] Here is another approach. Assume that a adults and c children tickets were sold. The Question can be modified as follows (5a +2c)/(a+c) = ? stmt says c/a = 3/2 ie c = 3a/2 ----------(1) substitute this ie the question. (5a + 3a)/(a +3a/2) simplifying, 16a/5a = 16/5 .. a definite answer So sufficient. Stmt 2 is not sufficient. hence A Senior Manager Joined: 22 Feb 2018 Posts: 354 Own Kudos [?]: 825 [0] Given Kudos: 34 Re: At a certain theater, the cost of each adult's ticket is$5 and cost [#permalink]
prashi82 wrote:
At a certain theater, the cost of each adult's ticket is $5 and cost of each child's ticked is$2. What was the average (arithmetic mean) cost of all adult's and children's tickets sold at the theater yesterday.

(1) Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2.

(2) Yesterday 80 adult's tickets were sold at the theater.

OA: A
Let the Adult's ticket price be $$T_{Adult}$$ and Child's ticket price be $$T_{Child}$$

$$T_{Adult}=5 \qquad T_{Child}=2$$

Let the number of Adults be $$A$$ and the number of children be $$C$$.

We have to find out the average cost of all tickets sold at the theater i.e We have to find $$\frac{A*T_{Adult}+C*T_{Child}}{A+C}......(1)$$

1) Yesterday the ratio of the number of children's tickets sold at the theater to the number of adult's tickets sold at the theater was 3 to 2.

$$\frac{C}{A}=\frac{3}{2}$$ ;$$C = \frac{{3A}}{2}......(2)$$

putting (2) and $$T_{Adult}=5 ; T_{Child}=2$$ in (1), we get

Average cost of all tickets sold $$= \frac{A*T_{Adult}+C*T_{Child}}{A+C} =\frac{A*5+\frac{3A}{2}*2}{A+\frac{3A}{2}} =\frac{8A}{\frac{5A}{2}}=\frac{16}{5}$$

Statement 1 alone is sufficient.

2)Yesterday 80 adult's tickets were sold at the theater.

We know about the number of Adult's ticket sold but are not aware about the number of children ticket sold.
Statement 2 alone is not sufficient
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