nate is helping to redisign his basement . he is in charge of choosing and buying the paint .he wants a specific shade of green, so he is going to combine blue and yellow paint in the ratio of 1:3 . if he needs 8 gallons of paint, how much yellow paint does he need to buy?
In a ratio of 1:3, there is a total of 1 + 3 = <<1+3=4>>4 parts.
To find out how much yellow paint is needed, we divide the total number of parts, which is 4, by the number of parts representing yellow paint, which is 3.
Since 8 gallons of paint is made up of 4 parts, each part represents 8/4 = <<8/4=2>>2 gallons.
Thus, Nate needs to buy 2 x 3 = <<2*3=6>>6 gallons of yellow paint. Answer: \boxed{6}.