Answer:
40mph
Explanation:
use the speed = distance/time formula.
1. The first car has a speed of 30mph and travels one mile so the equation can be written as 30mph = 1/t.
Rearrange to get t = 1/30
1/30 of an hour is 2 minutes.
2. The second car has a speed of 60 mph and travels one mile so the equation can be written as 60mph = 1/t
Rearrange to get t = 1/60
1/60 of an hour is 1 minute.
The time it took for the total journey is 1 + 2 = 3 minutes
Writing 3 minutes as a fraction of an hour:
3/60 = 1/20
So using the s = d/t formula to calculate the average speed the formula can be written as (the speed is unknown, time is 1/20 and the distance is 2 miles):
Speed = 2/(1/20) = 2x20/1 = 40
Therefore the average speed of that car is 40 mph.