38. A collection of coins are flipped. The outcomes are independent, and the ith coin comes...

38. A collection of ç coins are flipped. The outcomes are independent, and the ith coin comes up heads with probability cti9 i = 1 , n . Suppose that for some value of j , 1 < j < ç, á, = y. Find the probability that the total number of heads to appear on the ç coins is an even number.

39. Let A and  be mutually exclusive events of an experiment. If independent replications of the experiment are continually performed, what is the probability that A occurs before º

The system is said to work if a signal originating at the left end of the diagram can reach the right end, where it can only pass through a component if that component is working. (For instance, if components 1 and 4 both work, then the system also works.) What is the probability that the system works?