A paste used to cover a billboard is made by mixing the following ingredients by weight: 4 parts powder, 3 parts water, 2 parts resin, and 1 part hardener. To cover one billboard requires 30 pounds of this paste. How many total pounds of resin are required to cover 4 billboards?
- A6
- B8
- C24
- D48
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Correct answer: C
The ratio is , so the total parts is 10.
Since there are two parts resin, the fraction of resin is
So the amount of resin in 30 lb of paste (for 1 billboard) is
For 4 billboards, that would be 6 × 4 = 24 lb.