Question

Fill in the blank. In a drive thru performance study, the average service time for McDonald's is 209.79 seconds with a standard deviation of 9.9 seconds. A random sample of 67 times is taken. There is a 80% chance that the average drive-thru service time is greater than ________ seconds.

1)

210.81

2)	There is not enough information to determine this.

3)

201.46

4)

218.12

5)

208.77

Answer 1

Given that,

= / n = 9.9 / 67

P(Z > -0.84) = 0.80

z = -0.84

= z * + = -0.84 * 9.9 / 67 + 209.79 = 208.77

There is a 80% chance that the average drive-thru service time is greater than 208.77 seconds.

5)