In a propane-to-air ratio of 1:24, what percentage of the mixture is air?

In a propane-to-air ratio of 1:24, what percentage of the mixture is air?

• A. 4%
• B. Ninety-six percent air
• C. 50%
• D. 64%

Answer: (B)

Think of the ratio as 1 part propane to 24 parts air. Add them up to get the total: 1 + 24 = 25 parts. Air makes up 24 of those 25 parts, so the air fraction is 24/25 = 0.96, which is 96%. So the mixture is 96% air and 4% propane (the 1 part out of 25). The other percentages don’t fit because they don’t reflect 24 parts of air in a total of 25 parts.

Think of the ratio as 1 part propane to 24 parts air. Add them up to get the total: 1 + 24 = 25 parts. Air makes up 24 of those 25 parts, so the air fraction is 24/25 = 0.96, which is 96%. So the mixture is 96% air and 4% propane (the 1 part out of 25). The other percentages don’t fit because they don’t reflect 24 parts of air in a total of 25 parts.