[blstraub]

I need a little assistance with this problem...

Together, Americans drive about 5.0 x 109 miles per day, and their cars get an average of 22 miles per gallon of gas used. For each kilogram of gasoline used, about 3 kg of carbon dioxide is produced. How many kilograms of CO2 are emitted into the atmosphere by cars in the US each day? [1 gal = 3.5 kg]

I worked the problem out and got 2.4 x 10^9 kg... Which was one of the answers I had to choose from. The answer however was 2 x 10^9 kg (not 2.0). Is that correct? If so, what am I missing here? Wouldn't the correct number of significant figures be 2?

[Dan]

For each kilogram of gasoline used, about 3 kg of carbon dioxide is produced.

That's 1 sig fig.