SOLUTION: Wendy's Drive-Through Fast-food restaurants spend quite a bit of time studying the amount of time cars spend in their drive-through. Certainly, the faster the cars get through the

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Question 912932: Wendy's Drive-Through Fast-food restaurants spend quite a bit of time studying the amount of time cars spend in their drive-through. Certainly, the faster the cars get through the drive-through, the more the opportunity for making money. QSR Magazine studied drive-through times for fast-food restaurants, and found Wendy's had the best time, with a mean time a car spent in the drive-through equal to 138.5 seconds. Assume that drive-in times are normally distributed, with a standard deviation of 29 seconds. Suppose that Wendy's wants to institute a policy at its restaurants that it will not charge any patron that must wait more than a certain amount of time for an order. Management does not want to give away free meals to more than 1% of the patrons. What time would you recommend Wendy's advertise as the maximum wait time before a free meal is awarded?
On the TI-84 plus silver edition calculator I used normalcdf(.01,138.5,29)=1
I don't know if I'am doing the problem right, is 1 the answer?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
m = 138.5, sd = 29
z = invNorm(.99) = blue+%28x+-+mu%29%2Fblue%28sigma%29
29invNorm(.99) + 138.5 = x, the maximum wait time before a free meal is awarded