Question

Amie collects data on the fuel efficiency, in miles per gallon, and the mass, in kilograms, of

several different cars. She creates a scatter plot and determines that the line of the best fit for
the scatter plot has the equation y = 43.28 -0.011x, where y is the fuel efficiency, in miles per
gallon, and x is the mass, in kilograms. Based on this model, which of the following statements
is true?
O For every 100-kilogram increase in mass, the fuel efficiency of car decreases by about 0.4 miles
per gallon
O For every 100-kilogram increase in mass, the fuel efficiency of car increases by about 1.1 miles
per gallon
O For every 100-kilogram increase in mass, the fuel efficiency of car decreases by about 1.1 miles
per gallon
O For every 100-kilogram increase in mass, the fuel efficiency of car increases by about 0.4 miles
per gallon

Answer 1

For every 100-kilogram increase in mass, the fuel efficiency of car decreases by about 1.1 miles per gallon.

Explanation:

Fuel efficiency after x kg in mass:

y = 43.28 -0.011x

Thus, the slope is of -0.011 per x kg.

Increase of 100:

When x = 100, as the slope is negative, the efficiency will decay by:

-0.011*100 = -1.1

Decay of 1.1 miles per gallon, so the answer is:

For every 100-kilogram increase in mass, the fuel efficiency of car decreases by about 1.1 miles per gallon.