In an experiment, a heated cup of coffee is removed from a heat source and then allowed to cool in a room at a constant temperature. The x-axis represents the time since the cup was removed from the heat source (minutes), and the y-axis represents the temperature (°F). The scatter plot shows the temperature, in degrees Fahrenheit (), of the coffee immediately after removal and at 10-minute intervals thereafter. What is the approximate average rate of temperature decrease, in degrees Fahrenheit per minute, between 20 minutes and 40 minutes?
1
1.25
1.5
1.75
