A pressure control apparatus contains 3 electronic tubes The

A pressure control apparatus contains 3 electronic tubes. The apparatus will not work unless

all tubes are operative. If the probability of failure of each tube during

some interval of time is

0.04, what is the corresponding probability of failure of the

apparatus?

Since all three tubes should work, the probability of all the three working together is 0.96*0.96*0.96 = 0.8847

Therefore, the probabililty of the apparatus to not work is 1-0.8847 = 0.1153

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