The graph shows a city's daily rate of use of electricity (in millions of 28 kilowatts). Estimate the total daily 24- usage of electricity by summing the 20- area of rectangles. Use the left endpoints, then the right endpoints, 16- Millions of kilowatt-hours then give the average of those 12- results as the answer. Let the width of each rectangle be 2 hours. Midnight 4 A.M. BA.M. Noon 4 P.M. 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.)