The graph shows a city's daily rate of use of electricity (in millions 14 of kilowatts). Estimate the total 12- daily usage of electricity by 10- summing the area of rectangles. Use the left endpoints, then the Millions of kilowatt-hours right endpoints, then give the average of those results as the NA answer. Let the width of each rectangle be 2 hours. Midnight 4 A.M. 8 A.M. Noon 4 PM. 8 P.M. Midnight The estimate of the city's total daily usage of electricity for the given day, found by averaging the estimates using left and right endpoints, is million kw-hrs. (Round to the nearest whole number as needed.)