The time it takes a student to walk from the dorm to the chemistry lab follows roughly a Normaldistribution with a mean of 20 minutes and a standard deviation of 3 minutes. Suppose you are waitingfor your friend at the chemistry lab. She is walking from the dorm to the lab. Fifteen minutes have alreadypassed since the time she left the dorm. What is the probability she will arrive at the chemistry lab withinthe next 10 minutes (for a total walking time of less than 25 minutes)?

Amachine that produces a special type of transistor (a component of computers) has a 2% defective rate. the production is considered a random process where each transistor is independent of the others. (a) what is the probability that the 10th transistor produced is the first with a defect? (b) what is the probability that the machine produces no defective transistors in a batch of 100? (c) on average, how many transistors would you expect to be produced before the first with a defect? what is the standard deviation? (d) another machine that also produces transistors has a 5% defective rate where each transistor is produced independent of the others. on average how many transistors would you expect to be produced with this machine before the first with a defect? what is the standard deviation? (e) based on your answers to parts (c) and (d), how does increasing the probability of an event a↵ect the mean and standard deviation of the wait time until success?