An internet pharmacy advertises that it will deliver the over-the-counter products that customers purchase in 3 to 6 days. The manager of the company wanted to be more precise in its advertising. Accordingly, she recorded the number of days it took to deliver to customers.

number of days 0 1 2 3 4 5 6 7 8
probability 0 0 .01 .04 .28 .42 .21 .02 .02

What is the probability that a delivery will be made within the advertised 3-to-6-day period?