The time that a TA spends helping an individual student in office hours is exponentially dis- tributed with a mean of 10 minutes, and independent of the time spent with other students For an exponential distribution with i Suppose there is a homework due tomorrow, and there are 4 people ahead of you in line. a) The total time that it takesal 4 students ahead of you to receive help from the TA is a random variable. What is the mean of this total time? b) What is the probability that all 4 people ahead of you will each take at most 15 minutes?