If the ratio of brown cars to blue cars in a certain parking lot is 2:

Question

If the ratio of brown cars to blue cars in a certain parking lot is 2:3, how many brown cars are in the lot?

(1) There are 15 blue cars in the lot
(2) There are 25 cars total in the lot

msk0657 · Answer

Let Br - Brown cars , BL = Blue cars.

Given BR/BL = 2/3

=> BR = BL(2/3) --> Question stem.

Stat 1 : Given 15 blue cars in the lot . We get BR = 15(2/3) = 10 cars...Sufficient..

Stat 2 : BR + BL = 25.

BR = 25 - BL... Sub this value in question stem..

25 - BL = BL(2/3).

75 - 3BL = 2BL
 75 = 5BL => BL = 15. Then BR = 10 cars.. Sufficient...

IMO option D is correct answer..

OA please...Will correct if I missed anything...

Kurtosis · Answer

Brown : Blue = 2 : 3

St1: Blue = 15. If 3/5 corresponds to 15, 2/5 corresponds to 10. Number of brown cars = 10. Sufficient

St2: There are 25 cars in total. --> Question does not state that the parking lot contains only brown and blue cars. So we cannot determine the number of brown cars from the given statement. Not Sufficient

Answer: A

hsbinfy · Answer

in DS gmat questions both the argument give the same value whatsoever

you either take choice A or B both will give total number of cars as 25.Unless the values are diff in both cases(here for total number of cars) we can't assume what you saying above in statement 2.

Unless the question states there are more cars , we on our own can't assume there are more cars.

Answer will be D

Kurtosis · Answer

You are assuming that you get an unique solution using Statement 2. If there are only brown and blue cars then the number of brown cars is 10.

Consider a case where there are brown, blue and red cars and their ratio is 2:3:20. Number of brown cars = (2/25) * 25 = 2.

As seen above, Statement 2 results in multiple solutions and 2 brown cars doesn't match the value of the result obtained using Statement 1.

SomeOneUnique · Answer

If the ratio of brown cars to blue cars in a certain parking lot is 2:3, how many brown cars are in the lot?

(1) There are 15 blue cars in the lot 
 (2) There are 25 cars total in the lot

Brown  
  2x  
 
   Blue  
  3x

(I) 3x=15
x=5
We can find brown cars by substituting x as 5.
Hence statement I is sufficient.

(II) Total cars are 25.
2x+3x=5x
5x=25
x=5
x can be only 5 because cars can not be a fraction.
However, the parking lot may have a black car or a red car, then we can not equate 5x to 25.
Hence statement II is insufficient.

I do not consider myself to be a great mathematician but the correct option is A.

Pranavsawant · Answer

Brilliant, absolutely brilliant. GMAT Club at it's finest.

If the ratio of brown cars to blue cars in a certain parking lot is 2:

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