In a car dealer shop, 1/5 of the cars are red and 1/9 of the

Question

4. In a car dealer shop, 1/5 of the cars are red and 1/9 of the cars are blue. 1/3 of the red cars are used cars, and 3/5 of the blue cars are used cars. What portion of cars are new cars?

A) 3/8 B) 5/13 C) 5/36 D) 5/48 E) 8/45

remgeo · Answer

I am not getting any of the answers below. 
Say there are 45 cars in total. 

Red cars = 1/5th = 9
Blue cars = 1/9th = 5 

No of used red cars = 1/3rd of red = 3
No of used blue cars = 3/5 of blue = 3

Total used cars of 45 cars = 6
Assuming no other used cars, 
New cars = 39

Ratio of new cars to total = 39/45 = 13/15

christoph · Answer

E)...matrix:

____used___new___total
red__30___________90
blue_30___________50
total______________450

fill in the rest...

remgeo · Answer

. 

Hey, can you please explain this. I seem to be missing something

remgeo · Answer

Ok, I see where I am wrong. 
No of used red cars = 1/3rd of red = 3 Therefore new red is 6
No of used blue cars = 3/5 of blue = 3 Therefore new blue is 2. 

Total new = 8
Ratio = 8/45.

gamjatang · Answer

AWESOME! IMO, this is the best way deal with this type of question.

The answer is 8/45.

ywilfred · Answer

# of cars = n
# of red cars = n/5
# of blue cars = n/9
# of new red cars = 2/3 * n/5 = 2n/15
# of new blue cars = 2/5 * n/9 = 2n/45

# of new red and blue cars = 2n/15 + 2n/45 = 6n/45 + 2n/45 = 8n/45

So portion = 8/45

amy_v · Answer

I don't tink the question is explicit..But i cna make a slight modification to your pattern and get E

I took the totla number of cars as 90. So that makes 12+4 new cars in red and blue. Assuming there are no more new cars, 16/90=8/45.

NOw if you go ny the question alone, it should be 16/28 taking inot account only the red and blue, ignoring the rest... then it is 4/7

krisrini · Answer

Answer will be 8/45, if the question asks for What proprtion of cars are new red and blue cars. But since it doesn't explicity say that, how could this be 8/45. So I worked like remgeo to get 13/15.

Can someone correct me, if I am making a mistake.

My working were exactly same as that remgeo initial post.

rianah100 · Answer

This question looks screwed up to me ( pardon my language)-
It seems to indicate that there are other colors besides red and blue. So, no info is given on if there are other colored cars that are new/used. So, how can E be correct? It is only correct if the other colored cars are neither new nor used which is impossible.

automan · Answer

I agree with you. It is impossible to know the ratio.

In a car dealer shop, 1/5 of the cars are red and 1/9 of the

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