1) A laboratory network consisting of 25 computers was attacked by a c omputer virus

1) A laboratory network consisting of 25 computers was attacked by a c omputer virus. This virus enters each computer with a probability of 0.4, independently of other computers. What is the probability that  (a)At least ten computers are affected by the virus?    (b)More than ten computers are affected by the virus?

2) A clothing store has determined that 30% of the customers who enter the store will use a Visa credit card. Consider a collection of 15 customers who have entered to the store.    (a)How many of them you expect to use Visa card?   (b)What is the probability that more than five customers use Visa card?