The probability density function of X, the lifetime of a certain type of electronic device (measured in

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?

Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...