Four sheep are traveling the 250 m distance from the pasture back to the barn. after 45 seconds, their distances from the barn are as follows: dolly - 170 m, fluffy - 115 m, ellie - 90 m, ma - 200 m. according to average velocity, how would the sheep rank from fastest to slowest?

To answer this, you must first find the average velocity of each sheep.
This is the same as speed, but also includes direction.
Since the question only wants the sheep ranked from fastest to slowest, though, we don't need to worry about direction.
So it's really just calculating each sheep's speed and ordering it from highest to lowest.

Speed is calculated as Distance ÷ Time.

The problem tells us that the sheep have 250 meters to travel and the numbers listed for each sheep are the sheeps' distance from the barn after 45 seconds out of this 250 meters, NOT the total distance they have traveled.
This means that the numbers listed are the sheeps' current displacements.
To find how far each sheep has traveled after 45 seconds, subtract their current displacement from their original displacement of 250 meters.

Dolly's Speed:
The sentence "Four sheep are traveling the 250 m distance from the pasture back to the barn" is a distracter. Each sheep has traveled a different distance in 45 seconds, so the distance is not 250 m for each one.
Displacement = 170 m
Distance = Original Displacement - Current Displacement
250 - 170 = 80 m
The time is the same for all of them, though. The time is 45 seconds.
Time = 45 s
Speed = Distance ÷ Time
80 ÷ 45 = 1.7777...
Dolly's average speed is 1.78 m/s.

Fluffy's Speed:
Displacement = 115 m
Distance = 250 - 115 = 135 m
Time = 45 s
Speed = 135 ÷ 45 = 3
Fluffy's average speed is 3 m/s.

Ellie's Speed:
Displacement = 90 m
Distance = 250 - 90 = 160 m
Time = 45 s
Speed = 160 ÷ 45 = 3.5555
Ellie's average speed is 3.56 m/s.

Ma's Speed:
Displacement = 200 m
Distance = 250 - 200 = 50 m
Time = 45 s
Speed = 50 ÷ 45 = 1.1111...
Ma's average speed is 1.11 m/s.

As you can see, the lower the sheep's current displacement, the faster their speed.
List of each sheep's average speeds:
Dolly- 1.78 m/s
Fluffy- 3.00 m/s
Ellie- 3.56 m/s
Ma- 1.11 m/s

Now order these speeds from highest to lowest:
1. Ellie (3.56 m/s)
2. Fluffy (3.00 m/s)
3. Dolly (1.78 m/s)
4. Ma (1.11 m/s)

The list above is your answer.

Hope this helps!