Paints

[anshulseth]

A certain shade of gray paint is obtained by mixing 3 parts of white paint with 5 parts of black paint. If 2 gallons of the mixture is needed and the individual colors can be purchased only in one-gallon or half- gallon cans, what is the least amount of paint, in gallons, that must be purchased in order to measure out the portions needed for the mixture?
(A) 2
(B)
(C) 3
(D)
(E) 4


OA after few posts.
Please explain the working.

[agoyal2]

Choices B / D missing??

Anyway, The White and Grey are in a ratio of 3:5

So, to make 2 Gallons, you will need :
White = 2*3/8 Gallon = 3/4 Gallon (Purchase 1 Gallon)
Grey = 2*5/8 Gallon = 5/4 Gallon (Purchase 1.5 Gallon)

Total 2.5 Gallon minimum.

[anshulseth]

Oops, copy paste did it.

Once again the question is:
A certain shade of gray paint is obtained by mixing 3 parts of white paint with 5 parts of black paint. If 2 gallons of the mixture is needed and the individual colors can be purchased only in one-gallon or half- gallon cans, what is the least amount of paint, in gallons, that must be purchased in order to measure out the portions needed for the mixture?
(A) 2
(B) 2.5
(C) 3
(D) 3.5
(E) 4

[anshulseth]

@agoyal2

I missed u there. Please elaborate your explanation.

How come if it comes out to 3/4 gallon for white, you suggest to purchase 1 gallon. What's the logic?

White = 2*3/8 Gallon = 3/4 Gallon (Purchase 1 Gallon)
Grey = 2*5/8 Gallon = 5/4 Gallon (Purchase 1.5 Gallon)

[agoyal2]

From the question:

"The individual colors can be purchased only in one-gallon or half- gallon cans."

So, for 3/4 Gallon, you can either buy 2 half gallon cans or 1 one gallon can. similarly 5/4 Gallon = 1.25 Gallon = 1 Gallon can and 1 Half Gallon Can.

Whats the OA?

[ousek]

The White and Grey are in a ratio of 3:5

So, to make 2 Gallons, you will need :
White = 2*3/8 Gallon = 3/4 Gallon (Purchase 1 Gallon)
Grey = 2*5/8 Gallon = 5/4 Gallon (Purchase 1.5 Gallon)

Total 2.5 Gallon minimum.

Same strategy, same result.

OA ?

[anshulseth]

You are right.
OA is B