If each customer at the outdoor movie last night came in a c

Question

If each customer at the outdoor movie last night came in a car, what was the number of cars in which the customers came to the outdoor movie last night?

1) The average (arithmetic mean) number of customers per car coming to the outdoor movie last night was 2.

2) Total receipts at the outdoor movie last night were $4,500 at $5 per customer .

ID 04846

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Source:GMAT Prep Question Pack 1
Difficulty: Medium
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This is a fairly simple DS problem, however, I got tricked when I had to choose between C or E.

First, I thought this question was similar to this:
will-the-first-10-volumes-of-a-20-volume-encyclopedia-fit-128155.html?fl=similar

When combining C and E, I picked E because statement 1 said the average person per car was 2. The word "average" threw me off because it was an average and not a solid number of people. However, the OA is C.

1&2)

4500/5 = 900 customers

900/2 = 450 cars

Can anyone provide any similar DS questions whose tricks use averages in this way?

Show Answer

Official Answer

C

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zerosleep · Accepted Answer

Hi,
1) Tells us only about average no of person per car=2. It does not elicit anything about the total no of people or total no of cars in which they might have come. 
2) $4500 @ $5 per person menas in total there were 900 person. Again, we cant say how many cars.

While if we combine both, we know average = sum total of all quantities / no of quantities 
=> no of quantities = sum total of all quantities/average = 900/2 = 450.

Coming to your doubt obetween C and E, remember average reveals how many each can have if distributed equally. Hence the quantities which are moe than average will be balanaced bu those that have less than average. So in this case, some cars may have more than 2 person but then this extra will be offset by those that have less than 2 person per car. I hope this helps.

semwal · Answer

statement 1- avg 2 persons per car. fine. but how many cars? 4,5 or 20? not suff.
statement 2- no of people - 4500/5= 900. but came in how many cars? 900 @ 1/car or 450 @ 2/car?

both statements together- since avg 2 person per car, 900 can come in 900/2 = 450 cars only.
hence ans = C

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WillGetIt · Answer

Well, I have a doubt regarding this problem.

If the average number of customer per car is 02, we can have range of possibilities: (lets assume that car have seating capacity of 04 people)

So, here in our situation the "Averaging/Balancing" concept will not work.

This question is from QPACK 01 and I think answer should be (E).

Official explanation incorrectly mentions (C).

Any expert replies please.

Thanks

IanStewart · Answer

This is really just a ratio question; Statement 1 about 'average customers per car' is really just telling us that the ratio of customers to cars is 2 to 1. So if we know, from Statement 2, there were 900 customers, then using S1 there were 450 cars, and the answer is C.

The official answer is correct. The seating capacity of the cars is not relevant to the question. The question only talks about how many customers actually occupied the cars, not how many seats were in the cars.

GMATinsight · Answer

Hi Vikasbansal227,

The Average Customer per car is Defined as follows

Average Customer per Car = (Total Customers) / (Total No. of Cars)

i.e. Total No. of Cars = (Total Customers) / (Average Customer per Car)

Statement 1: Average Customer per Car=2

i.e. Total Customers = (2) * (Total No. of Cars)

But Since the  Total No. of Customers is unknown  therefore

NOT SUFFICIENT

Statement 2: Total receipts at the outdoor movie last night were $4,500 at $5 per customer 
Total Customer = Total Receipts / Receipt per customer = 4500/ 5 = 900
But the The relation between Total Number of Customers and No. of Cars is unknown, Therefore

NOT SUFFICIENT

Combining the two statements:

From Statement 1: Total Customers = (2) * (Total No. of Cars)
From Statement 1: Total Customers = 900

i.e. (Total No. of Cars) = 900/2 = 450
  SUFFICIENT

Answer: Option  C

Please Note: It's not a good Idea to doubt the Answers of Official Resource. Official resource is made after a lot of iterations and research and corrections.

nks2611 · Answer

It is straight c
Although initially it looks E, but as you go through it carefully then we know we have given no. Of passengers and also by combining we get to know about aveg of passanger per car so it is C after all

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If each customer at the outdoor movie last night came in a c

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If each customer at the outdoor movie last night came in a c

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