Acomputer company uses 6 characters to create their serial number identification for products. the first 3 characters are any single digit number but no character can repeat in those first 3 characters. the next two characters must be a letter and those two letters cannot be the same. the last space can be any number or letter without any restriction. how many unique serial numbers are possible?
a. 11,232,000
b. 24,336,000
c. 15,912,000
d. 16,848,000

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?