Gasoline varies in cost from $0.94 to $1.14 per gallon. If a car’s mileage varies from 16 to 24 miles per gallon, what is the difference between the most and least that the gasoline for a 480-mile trip will cost? Choose the most appropriate option
A) $15.20
B) $15.30
C) $15.40
D) $15.50
E) $15.60
Solution:   We know that the per gallon cost of gasoline varies from $0.94 - $1.14.   Now we want to find the MAXIMUM difference between the least amount of money spent on gasoline and the largest amount of money spent i.e. to calculate max. trip cost - min. trip cost.   Mileage is given to be 16 to 24 miles per gallon, thus to travel 480 miles you will need gasoline in the range 480/24 to 480/16 which is 20 to 30 gallons.   So, for these 20 gallons and 30 gallons of gasoline the cost is as follows: (divide this task into 2 parts, 1 for 30 gallons and 2nd one for 20 gallons).   $15.40ase 1: for 30 gallons the cost is 30*0.94 to 30*1.14 which is $28.20 to $34.20   $15.40ase 2: for 20 gallons the cost is 20*0.94 to 20*1.14 which is $18.80 to $22.80   Thus, the maximum cost of the 480 mile trip is $34.20 and minimum is $18.80   so the difference is $34.20 - $18.80 = $15.40   Answer: $15.40 34.20 -  18.80= 
<gadget id="calculator"> 34.20 -  18.80</gadget>
<output>15.4</output>
$15.40   Answer: $15.40
<result>C</result>
Gasoline varies in cost from $0.94 to $1.14 per gallon. If a car’s mileage varies from 16 to 24 miles per gallon, what is the difference between the most and least that the gasoline for a 480-mile trip will cost?