Answer:
18.6 i think
Step-by-step explanation:
If a question has four possible answers, and you are strictly guessing regarding which of them is correct, then the chances of your choosing the correct one from the four is 1 in 4, or 0.25.
The components operate independently, so the probability of "total" system failure is the same as the product of each probability of component failure. That is, if

denotes the event that component

fails, then

The

are independent and identically distributed, so

for all

. So