neoreaves Posted May 10, 2009 Share Posted May 10, 2009 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 © 3 (d) 3.5 (e) 4 Quote Link to comment Share on other sites More sharing options...
rajatmeh Posted May 10, 2009 Share Posted May 10, 2009 In 2 gallons of mixture White paint required = 3*2/8=3/4 gallon ==> need to buy 1 gallon can Black paint required = 5*2/8=5/4 gallon ==> need to buy 1 (1 gallon can) and 1(1/2 gallon can). Total = 1 + 1 + 1/2 = 2.5 gallon Quote Link to comment Share on other sites More sharing options...
genius_in_the_gene Posted May 10, 2009 Share Posted May 10, 2009 2.5 it is Quote Link to comment Share on other sites More sharing options...
buskool Posted May 11, 2009 Share Posted May 11, 2009 2.5 it is. Quote Link to comment Share on other sites More sharing options...
aaadith Posted May 12, 2009 Share Posted May 12, 2009 3x+5x=2 8x=2 x=0.25 white = 3x = 0.75 = 1*(1 gallon container) black = 5x = 1.25 = 1 * (1 gallon container) + 1*(0.5 gallong container) answer : 2.5 gallons Quote Link to comment Share on other sites More sharing options...
gmat.760 Posted May 12, 2009 Share Posted May 12, 2009 The parts of the white and black mixture is 3:5 so 3/8*2 gallons of white and 5/8 *2 gallons of black are required which is 0.75 and 1.25 respectively, since it is available only in 1/2 and 1 gallon you requie 1 gallon for white and 1.5 gallons for Black, so it is 2.5 gallons. Answer is B Quote Link to comment Share on other sites More sharing options...
abhishek_mumbai Posted May 12, 2009 Share Posted May 12, 2009 make a ratio.. for every gallon.. we need 3/8 of white and 5/8 of black. so for 2 gallons, we need 6/8 of white i.e. 3/4 gallon and 10/8 of black i.e. 5/4 gallons now, as we can buy in 1 and 1/2 parts.. we need 1 gallon of white and 1.5 gallons of black.. total 2.5 gallons we still have 1/4 gallon of white and 1/4 gallon of black remaining.. I'll see if I can use it for my store room (at least white) :) Quote Link to comment Share on other sites More sharing options...
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