INV is close to INV max 5 cars Hence a better estimate of the actual peak

# Inv is close to inv max 5 cars hence a better

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INV is close to INV max = 5 cars. Hence, a better estimate of the actual peak throughput is λ = 5 / 167 . 9 cars per second, assuming that CT = 167.9 seconds is accurate for the 90- minute lunch rush. (The original QSR study actually indicates that this is CT for the time windows 11am-2:30pm and 4pm-7pm). A first-pass at a corrected estimate is the following: (a) 5,400 seconds in 90 minutes (b) Assuming INV = 5 cars when CT = 167 . 9 seconds, this implies 5 , 400(5 / 167 . 9) = 160 cars served per restaurant during that period at current service speed. 1
(c) 77.9 seconds, is what McD’s must shave off its average drive-through time to hit its 90-second target. (d) At CT = 90 seconds, they could service at most 5 , 400(5 / 90) = 300 cars in that period on average, assuming INV = INV max = 5 cars at this new CT. This would be their capacity (recall the ovens at Varsity Subs). So they could service at most an extra 300 - 160 = 140 cars, combining the result with part 2. (e) Assuming \$5 revenue per car, this yields (\$5)(140) = \$700 extra revenue per day for each restaurant. (f) Assuming 300 good drive-through days per year, this amounts to (\$700)(300) = \$210,000 in additional peak period revenue earned per restaurant annually. (g) Across 13,673 locations, this totals \$2.87 billion, or about 15% of their current annual revenues of around \$20 billion. In general, all the numbers (except 77.9 and 5,400) stated in the figure must be multiplied by INV INV max = 5.