fraction fun

[tatumpecoach]

ok, here is a problem. not sure how to work it.




A fruit drink has 4/7 water and 2/9 fruit juice (by weight). Other additives (primarily sugar) make up what fraction of its weight.




I don't simply multiply 4/7 by 2/9 do I? little stumped on the "what fraction of its weight is other additives".

 

[tkhunny]

A fruit drink has 4/7 water and 2/9 fruit juice (by weight). Other additives (primarily sugar) make up what fraction of its weight.

Looks like a subtraction problem, to me.

The whole drink is unity, one (1).

Throw out the water.
1 - 4/7 = 7/7 - 4/7 = 3/7
This is the fraction that ISN'T water.

Throw out the fruit juice.
3/7 - 2/9 = 27/63 - 14/63 = 13/63
This is the fraction that is neither water nor fruit juice.