# Question

The probability density function of X, the lifetime of a certain type of electronic device (measured in hours), is given by

(a) Find P{X > 20}.

(b) What is the cumulative distribution function of X?

(c) What is the probability that, of 6 such types of devices, at least 3 will function for at least 15 hours? What assumptions are you making?

(a) Find P{X > 20}.

(b) What is the cumulative distribution function of X?

(c) What is the probability that, of 6 such types of devices, at least 3 will function for at least 15 hours? What assumptions are you making?

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