Farina wrote:
Fiber X cereal is 55% fiber. Fiber Max cereal is 70% fiber. Sheldon combines an amount of the two cereals in a single bowl of mixed cereal that is 65% fiber. If the bowl contains a total of 12 ounces of cereal, how much of the cereal, in ounces, is Fiber X?
X----------------------Max
55---------65----------70
65-55=10----------70-65=5
Write in cross direction:
x/m = 5/10
We can do the second half in an alternative method as well:
x:m:t = 5:10:15
x/t = 5/15 (= 1/3)
Given amount of fiber, t=12 ounces
Therefore, we can calculate the amount of fiber as well: Ratio * t = (x/t) * t = (1/3) * 12 = 4 ounces
You choose your favourite method!