Fill in the blanks!

Time Elapsed (hr) - Distance Run (mi)
2 - 13.5
4 - 27.5
7 - 48.5

Larry recorded his time as he ran.
What was his average speed from hour 2 to hour 4? _
What was his average speed from hour 4 to hour 7? _
Did he speed up, slow down, or stay the same? _

1 answer

To find the average speed over the given time intervals, you can use the formula for average speed:

\[ \text{Average Speed} = \frac{\text{Distance}}{\text{Time}} \]

1. From hour 2 to hour 4:

  • Distance at hour 2: 13.5 miles
  • Distance at hour 4: 27.5 miles
  • Distance covered from hour 2 to hour 4: \[ 27.5 - 13.5 = 14 \text{ miles} \]
  • Time duration from hour 2 to hour 4: \[ 4 - 2 = 2 \text{ hours} \]
  • Average Speed from hour 2 to hour 4: \[ \text{Average Speed} = \frac{14 \text{ miles}}{2 \text{ hours}} = 7 \text{ miles per hour} \]

2. From hour 4 to hour 7:

  • Distance at hour 4: 27.5 miles
  • Distance at hour 7: 48.5 miles
  • Distance covered from hour 4 to hour 7: \[ 48.5 - 27.5 = 21 \text{ miles} \]
  • Time duration from hour 4 to hour 7: \[ 7 - 4 = 3 \text{ hours} \]
  • Average Speed from hour 4 to hour 7: \[ \text{Average Speed} = \frac{21 \text{ miles}}{3 \text{ hours}} = 7 \text{ miles per hour} \]

Conclusion:

  • Average speed from hour 2 to hour 4: 7 miles per hour
  • Average speed from hour 4 to hour 7: 7 miles per hour

Did he speed up, slow down, or stay the same?

Since the average speeds over both time intervals are the same (7 miles per hour), Larry stayed the same.