Question 1) The average height of fully grown yucca plants follows a Normal distribution with mean = 250 centimeters and standard deviation = 40 centimeters.

1)What height would a fully grown yucca plant need to have so that the probability of a yucca plant having a height less than this plant is 0.65. Write out the equation we would need to solve in order to answer this question, then use the qnorm() function in R to find this score.

Question2) The time between phone calls for a customer service hotline follows an Exponential distribution with parameter = 1/10 minutes.

2-1) It has been 3 minutes since the last phone call. what is the probability that the next phone call will not occur for a total of at least 12 minutes?

2-2) After the customer service line has received three more calls, it will close down for the night. Assume all incoming calls are independent of one another. How long do we expect the customer service line to stay open? How much do we expect the close time to vary around the expected time?

Question3) The number of years before the next book in your favorite series comes out follows an exponential distribution. The next book is expected to be published in 4 years.

3)it has been 5 years. what is the probability that the book will take 6 or more years to come out?