40. Wendy\'s Drive-Through Fast-food restaurants spend bit of time studying the

Question

40. Wendy's Drive-Through Fast-food restaurants spend bit of time studying the amount of time cars spend in their dhce throughs. Certainly, the faster the cars get through the driv through, the more the opportunity for making money. QSR Magazine studied drive-through times for fast-food restau and found Wendy's had the best time, with a mean time spent in the drive-through of 138.5 seconds. Assuming drive-through times are normally distributed with a standard deviation of end quite a ive. e- 29 seconds, answer the following. (a) What is the probability that a randomly selected car will get through Wendy's drive-through i less than 100 seconds? (b) What is the probability that a raudomly selected car will spend more than 160 seconds in Wendy's drive-through? Wendy's drive-through? in Wendy's drive-through? Why? (c) What proportion of cars spend between 2 and 3 minutes in (d) Would it be unusual for a car to spend more than 3 minutes

Explanation / Answer

for normal distirbution zscore =(X-mean)/std deviation

a) P(X<100) =P(Z<(100-138.5)/29)=P(Z<-1.3276)=0.0922

b) P(X>160)=1-P(Z<(160-138.5)/29)=1-P(Z<0.7414)=1-0.7708=0.2292

c) P(120<X<180)=P((120-138.5)/29<Z<(180-138.5)/29)=P(-0.6379<Z<1.4310)=0.9238-0.2618 =0.6620

d)P(X>180)=P(Z>1.4310)=1-P(Z<1.4310)=1-0.9238=0.0762

as above probability is greater than 0.05 level therefore it is not unusual

Related Questions

Navigate

• Browse (All)
• Browse 4
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.