The velocity is a quantity that characterizes the kinematic state of a body. In general, the speed is defined as the ratio between space and time. Although the speed of a body may be different at different times of a movement, you can define an average speed as the total distance traveled divided by the time elapsed.
v = Δd/Δt
Δd → Distance traveled in the interval Δt
In this case:
Δd = 12 miles, and Δt = 10 minutes
v = 12 miles/10 minutes = 1.2 miles/minutes
In this case the unit of measurement is miles/minutes. To express this unity in the international system(S.I), the miles should be expressed in meters and the minutes, in seconds:
1 mile = 1609.3 meters
1 minute = 60 seconds.
12 miles = 19311.6 meters
10 minutes = 600 seconds
v = (19311.6/600) = 32.19 meters/second
So the average speed of sally, is 1.2 miles/minutes or 32.19 meters/second
I'm surprised that nobody responded with the most typical unit rate for speed: miles per hour.
Let's come back to the question. Sally travelled 12 miles in 10 minutes. To make things easier, let's first make this a unit rate for minutes. If Sally travels 12 miles in 10 minutes, we can find how long she travels in 1 minute:
12 (miles) / 10 (minutes) = 1.2 (miles per minute)
Therefore, Sally travels 1.2 miles per minute.
Now, let's take this unit rate and convert to a new unit rate: miles per hour.
As we know, there are 60 minutes in an hour. If Sally travels 1.2 miles in 1 minute, she travels 1.2 miles times 60 minutes in 60 minutes.
1.2 (miles per minute) * 60 (minutes in an hour) = 72 (miles per hour)
Therefore, Sally is travelling at 72 miles per hour.
To calculate the average speed you use:
In the equation Sally travels 12 miles ----> 12 Miles
In the equation Sally travels for 10 min ---> 10 Min
12 divided by 10 = 1.2 miles per minute
Hope this helps! :)
really simple to get the answer follow this formula
average speed (unit rates) = how fast she ran ÷ the time she ran in
average speed = 12 ÷ 10
average speed = 1.2 miles per min
you can check this by doing 1.2 x 10 = 12 which how much she ran