Question

Use the data in the following table, which lists drive-thru order accuracy at popular fast food chains. Assume that orders are randomly selected from those included in the table.

	Drive-thru Restaurant
	A	B	C	D
Order Accurate	313313	268268	244244	141141
Order Not Accurate	3838	5959	3636	1515

If two orders are selected, find the probability that they are both from Restaurant D.

a. Assume that the selections are made with replacement. Are the events independent?

b. Assume that the selections are made without replacement. Are the events independent?

Answer 1

a)The probability of getting two orders from Restaurant D is (156/1114)*(156/1114)=0.0196

The events are independent because choosing the first order does not affect the choice of the second order.

b)

the probability of getting two orders from Restaurant D is (156/1114)*(155/1113)=0.0195

The events are not independent because choosing the first order affects the choice of the second order.