Question

Estimate the number of gallons of gasoline consumed by the total of all automobile drivers in the U.S., per year. Suppose that there are about 3 × 10^8 people in the United States, approximately half of the them have cars, each car drives an average of 12,000 mi per year, and consumes a gallon of gasoline for each 20 mi?

Answer 1

Answer:

$G = 9 \times 10^{10} gallons$

Explanation:

Total number of people in US is  $N_p = 3 \times 10^8$

Only half of them have cars. So, Number of cars in US

$N_C = \frac{N_p}{2} \\\\N_C = \frac{3 \times 10^8}{2} \\\\N_C = 1.5 \times 10^8$

Each cars drives 12000 miles, so total distance travelled by all of these cars combined

$D = N_C \times 12000\\\\D = 1.5 \times 10^8 \times 12000\\\\D = 1.8 \times 10^{12} miles$

To travel 20 miles, we need 1 gallon of gasoline

Amount of gasoline required to travel one mile is  $\frac{1}{20}$ gallons

Amount of gasoline required to cover the distance 'D'.

$G = D \times \frac{1}{20} \\\\G = 1.8 \times 10^{12} \times \frac{1}{20} \\\\G = 9 \times 10^{10} gallons$

Amount of gasoline required to cover the distance 'D'.

$G = D \times \frac{1}{20} \\\\G = 1.8 \times 10^{12} \times \frac{1}{20} \\\\G = 9 \times 10^{10} gallons$

Answer 2

3 x 108 is roughly 300 people. Half of them have cars. Half of 300 = 150. 150 x 12000 = 1,800,000 miles driven. Each car gets 20mpg. Solve for the # of gallons consumed.