# so my math homework says, "sally traveled 12 miles in 10 minutes, what is her average speed (unit rate)?" i need help :))

electreto05 | Certified Educator

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.

then:

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

rsarvar1a | Student

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.

So:

1.2 (miles per minute) * 60 (minutes in an hour) = 72 (miles per hour)

Therefore, Sally is travelling at 72 miles per hour.

brokenarsenal | Student

To calculate the average speed you use:

Distance

---------

Time

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! :)

jesterswag | Student

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