# If white balls have a mass of 5.0 grams and black balls have a mass of 2.0 grams, in a box containing white and black balls with #2/3# of the balls being white, what is the average mass of a single ball in this box?

##### 1 Answer

Sep 2, 2015

Average mass (per ball)

#### Explanation:

If

then we could group the balls into groups of 3 with 2 white balls and 1 black ball in each group.

Each group would weight

and since there are

the average weight would be