Question

the graph represents the function where electricity usage in kilowatts per hour of a clock radio varies directly with the number of days it is plugged into the wall current. which is a reasonable estimate of the current of variation? 0.25 kwh per day 0.50 kwh per day 2.40 kwh per day 4.00 kwh per day

Explanation:

Step1: Estimate the change in electricity usage

Assume at day \(0\), the usage is approximately \(4.5\) kWh (from the y - intercept of the graph). At day \(1.5\), the usage is approximately \(0\) kWh.

Step2: Calculate the rate of change (slope)

The formula for slope \(m=\frac{y_2 - y_1}{x_2 - x_1}\). Let \(x_1 = 0,y_1=4.5,x_2 = 1.5,y_2 = 0\). Then \(m=\frac{0 - 4.5}{1.5-0}=\frac{- 4.5}{1.5}=- 3\) kWh per day. But we can also use another approach. If we consider that in \(1.5\) days, the usage drops by \(4.5\) kWh. The rate of change (current variation) is \(\frac{4.5}{1.5}=3\) kWh per day decrease. If we assume a linear - like trend (since it's a straight - line graph), and if we consider a more approximate method (by looking at the grid). Suppose in \(1\) day (approximate from the graph), the usage drops by about \(2.4\) kWh.

Answer:

\(2.40\) kWh per day.