232 . A certain shade of gray paint is obtained by mixing 3 parts of white paint with 5parts of black paint.If 2 gallons of the mixture is needed and the individual colors can be purchased only in one gallon or half galloncans,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

答案是2

请教各位兄弟姐妹，这道题的解题思路 应该是怎样的呢？？谢谢啦

这题我明明见有人问过，答案是2.5啊。

可知道得到一份gray paint ，需要3/8份white paint ， 5/8份black paint

可知道得到2 gallons gray paint ，需要3/4gallon white paint ， 5/4 gallons black paint

所以需要1 gallon white paint ， 1.5 gallon black paint，共2.5