Question

A website manager has noticed that during the evening​ hours, about 0.25 people per minute check out from their shopping cart and make an online purchase. She believes that each purchase is independent of the others.

c) What is the mean time between​ purchases?

​d) What is the probability that the time to the next purchase will be between 33 and 66 minutes?

Answer 1

Let X be the random variable = no of people checking out per minute from their shopping cart;

where X Po (0.25)

(c) The mean time between purchases = 1/ = 1/0.25 = 4.00

ANS : 4

(d) P (next purchase will between 33 and 66)

We will use the exponential funciton in excel EXPON.DIST( x ,, cummulative)

= EXPON.DIST(66, 0.25 , TRUE) - EXPON.DIST(66, 0.25,TRUE)

= 1.000 - 0.99974 = 0.000261

ANS: 0.000261