A certain shade of Grey paint is obtained by mixing 3 parts of white with 5 parts of black paint.if 2 gallons of mixture is needed and the individual colours can be purchased only in one gallon or half gallon cans, what is the least amount of paints in gallons that must be purchased in order to measure out the portions needed for mixture?
A.2 B.2 and 1/2 C.3 D.3 and 1/2 E.4

• 2 and 1/2
  Solution:
  3/4 of white paint
  5/4 of black paint.
  but the question says individual paints can be bought only in half gallon and full gallon.
  so for white paint you will have to buy (1/2 gallon + 1/2 gallon) to fullfil 3/4 gallons.
  And for black you will have to buy (1 full gallon + 1/2 gallon) to fullfil 5/4.
  
  So total----> (half+half+one+half)---> two and half! :)
• 11 years agoHelpfull: Yes(10) No(1)
• @saumya: for white how can we decide (1/2 gallon+1/2 gallon) to fulfill 3/4 gallons...plz explain
• 11 years agoHelpfull: Yes(7) No(0)
• option a i.e. 2 gallon is needed
  as 3/4w+5/4b=8/4g
  and 3/4+5/4=2
• 11 years agoHelpfull: Yes(2) No(7)
• E. 4 gallons..
  white --> w = 1.5 = 3/2
  black --> b = 2.5 = 5/2
  w/b = (3/2)/(5/2)=3/5 which is the required ratio..
  mixing this will give double amount of solution i.e. 2.5+1.5=4 gallons :)
• 10 years agoHelpfull: Yes(2) No(1)
• A certain shade of Grey paint is obtained by mixing 3 parts of white with 5 parts of black paint.if 2 gallons of mixture is needed and the individual colours can be purchased only in one gallon or half gallon cans, what is the least amount of paints in gallons that must be purchased in order to measure out the portions needed for mixture?in this how it comes as 3/4
• 10 years agoHelpfull: Yes(0) No(0)
• 1.5 + 2.5 =4 gallon
  for 2 gallon ratio should be 3:5=.75/1.25 but they can"t be bought in 1 and 1/2 can so multiply them by .75*2=1.5 and 1.25*2=2.5
  & a/q 1./2.5=3/5 so ans is 4
• 8 years agoHelpfull: Yes(0) No(0)