Answer: B 0.5 kWh per day
Step-by-step explanation:
Since 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
The constant of variations will be the gradient ( slope ) of the graph.
Gradient = (Y2 - Y1)/(X2 - X1)
Where X1 = 2, X2 = 6, Y1 = 0.5, Y2 = 1.5
Substitute all the values into the formula
Gradient = (1.5 - 0.5)/( 6 - 4 )
Gradient = 1/2
Gradient = 0.5.
Therefore, a reasonable estimate of the constant of variation is 0.5 kWh per day
