Question

Comparing Speeds
A graph titled Arnie's Airplane has time (minutes) on the x-axis and distance (miles) on the y-axis. A line goes through points (0, 0) and (2, 10). A 2-column table with 3 rows titled Bernie's Biplane. Column 1 is labeled Time (minutes) x with entries 3, 5, 8. Column 2 is labeled Distance (miles) y with entries 21, 35, 56.

Find each slope from the graph and table to compare the constant speeds of the two airplanes.

What is the constant speed (slope) of Arnie’s airplane?

What is the constant speed (slope) of Bernie’s biplane?

Who flew faster?

Answer 1

Slope = change in distance ÷ change in time.

Arnie: using (0,0) and (2,10), slope = (10−0)/(2−0) = 10/2 = 5 miles per minute (5 mi/min = 5×60 = 300 mi/hr).

Bernie: from the table, (5−3) gives (35−21)/(5−3) = 14/2 = 7 miles per minute (also (56−35)/(8−5)=21/3=7). So 7 mi/min = 7×60 = 420 mi/hr.

Who flew faster? Bernie’s biplane (7 mi/min > 5 mi/min).