Suppose the time it takes Alex to do this exam is exponentially distributed with parameter 3 per hour, and the time it takes Ben to do the exam is exponentially distributed with parameter 2per hour. Assume that these two times are independent.(a) What is the probability that Alex finishes before Ben?(b) What is the expected time in minutes until the first one finishes this exam?(c) What is the probability that neither Alex nor Ben finishes the exam within 3 hours?
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
Suppose the time it takes Alex to do this exam is exponentially distributed with parameter 3 per hour, and the time it takes Ben to do the exam is exponentially distributed with parameter 2
per hour. Assume that these two times are independent.
(a) What is the
(b) What is the expected time in minutes until the first one finishes this exam?
(c) What is the probability that neither Alex nor Ben finishes the exam within 3 hours?
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