Best Electronics, Inc. offers a "no hassle" returns policy. The number of items returned per day follows the normal distribution. The mean number of customer returns is 10.4 per day and the standard deviation is 2.3 per day.
(a) In what percent of the days are there 7.5 or fewer customers returning items? (Round z-score computation to 2 decimal places and your final answer to 2 decimal places.)
(b) In what percent of the days are between 11 and 12 customers returning items? (Round z-score computation to 2 decimal places and your final answer to 2 decimal places. )
(c) Is there any chance of a day with no returns?