An average rate of change on a scatterplot uses the two dots at the requested times, not the whole cloud of data. Divide the change in the vertical value by the change in the horizontal value; the axis labels give the units. The total pressure increase alone is not a rate per minute.
Hints
- Hint 1
Each point on a scatterplot pairs a time on the horizontal axis with its recorded pressure on the vertical axis. Read the dots at the two requested times, rather than fitting a line through all the dots.
- Hint 2
An average rate of change is the change in pressure divided by the change in time. Subtract the endpoint values in the same order on top and bottom. Which change gives kPa, and which gives minutes?
Step-by-step
Use the two endpoint dots
Step 1Read the pressures at the requested times
The graph labels the dots at and as and . A coordinate pair lists time first and pressure second, so the endpoint pressures are kPa and kPa.
- Step 2
Write the average rate
For an average rate of change, divide the pressure change by the time change. Take later minus earlier in both places so each pressure stays paired with its time:
The dots between these times don't change the average rate over the requested interval.
- Step 3
Calculate and interpret the rate
Type into Desmos. It shows , so the recorded pressure increased at an average rate of kPa per minute from minute to minute . Grid in 6.