Answer:
The extra cost of gasoline is $16.65
Explanation:
Let’s write the complete question;
The speed of your automobile has a huge effect on fuel consumption. Traveling at 65 miles per hour (mph) instead of 55 mph can consume almost 20% more fuel. As a general rule, for every mile per hour over 55, you lose 2% in fuel economy. For example, if your automobile gets 30 miles per gallon at 55 mph, the fuel consumption is 21 miles per gallon at 70 mph.
If you take a 400-mile trip and your average speed is 80 mph rather the posted speed limit of 70 mph, what is the extra cost of fuel if gasoline costs $ 3.00 per gallon? your car gets 30 miles per gallon (mpg) at 60 mph.
solution;
In this question, we are to calculate the extra cost of gasoline resulting from exceeding the supposed speed limit on a trip by a car given the cost of gasoline.
We proceed as follows;
Driving the speed limit:
Speed: 70 miles per hour (mph)
Fuel efficiency: 30 * [1-(70-60)*(2%)]= 30* 0.8 =24 mpg
Fuel amout for you 400-mile trip: 400/24= 16.67 gallon
Cost of fuel: 16.67 * $3= $50.01
Cost of time: 400/70 = 5.71 hrs
Exceeding the speed limit:
Speed: 80 miles per hour (mph)
Fuel efficiency: 30 *[1- (80-60)*(2%) ]= 30* 0.6 =18 mpg
Fuel amout for you 400-mile trip: 400/18= 22.22 gallon
Cost of fuel: 22.22 * $3= $66.66
Now to find the extra cost of fuel, we simply subtract the cost of fuel while exceeding the speed limit from the cost of fuel while driving within the speed limit.
That would be $66.66 - $50.01 = $16.65
