The density of air is $1.19g/L$. What is the air's mass, in kilograms, in a room that measures $14.5\cdot16.5\cdot8.0$ feet?
The room is is $14.5 \cdot 16.5 \cdot 8.0 = 1914$ cubic feet. We should probably convert that to liters.
One feet is $12$ inches so we got $22968$ cubic inches.
One inch is $2.54$ centimeters so we got $58338.72$ cubic centimeters.
One cubic centimeter is one milliliter, so we got $58338.72$ milliliters.
That's $58.33872$ liters.
So, if the density of air is $1.19$ grams for each liter, it means that the mass of air is $58.33872 * 1.19 = 69.4230768$ kilograms.
The answer is like $69kg$ then.
... Which is apparently wrong. The book says it is $64kg$. What did I do wrong?
You made an error in your conversions:
You aren't converting from feet to inches your converting from $ft.^3$ to $in.^3$ so instead of $12:1$ you must use $12^3 = 1728:1$ same thing with inches to cm