# A box contains 1085 grams total weight of marbles and ball bearings There are two marbles for every three ball bearings. If each marble weighs 2.0 grams and each ball bearing weighs 9.0 grams, how many marbles are in the box?

Feb 26, 2017

70

#### Explanation:

$\left(\text{marbles")/("ball bearings}\right) = \frac{m}{b} = \frac{2}{3}$

The unit weight of this combination (set) is:

$\left(2 \times 2 g r a m s\right) + \left(3 \times 9 g r a m s\right) = 31 g r a m s$
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The total count of this unit weight in all of the combined mass is:

$1085 \div 31 = 35 s e t s$

Each set has 2 marbles so the total count of marbles is:

$35 \times 2 = 70$