1. During a particular week the university’s information technology office received 20 service orders for problems with printers of which eight were laser printers and 12 were inkjet models. A sample of five of these service orders is to be selected for inclusion in a customer satisfaction survey.

(a) What is the probability that 4 of the selected service orders for inclusion in the customer satisfaction survey will be from laser printers?

(b) What is the probability that less than half of the orders selected for inclusion in the customer satisfaction survey will be from laser printers?

2. A spyware is trying to break into a system by guessing its password. It does not give up until it tries 1 million different passwords. What is the probability that it will guess the password and break in if by rules, the password must consists of:

(a) 6 different lower-case letters of the English alphabet.

(b) any 6 lower-case letters of the English alphabet.

 

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3. Compute the reliability of the following system if each component functions independently of the others with probability 70%. D A O B E G 3. Compute the reliability of the following system if each component functions independently of the others with probability 70%. D A O B E G