Answer:
36.58% probability that one of the devices fail
Step-by-step explanation:
For each device, there are only two possible outcomes. Either it fails, or it does not fail. The probability of a device failling is independent of other devices. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
A total of 15 devices will be used.
This means that 
Assume that each device has a probability of 0.05 of failure during the course of the monitoring period.
This means that 
What is the probability that one of the devices fail?
This is 


36.58% probability that one of the devices fail
9514 1404 393
Answer:
x = 5, x = 11
Step-by-step explanation:
Set f(x) = 0 and solve for x.
0 = (x -8)² -9
9 = (x -8)² . . . . . add 9
±√9 = x -8 . . . . . take the square root
±3 +8 = x . . . . . . . add 8
That is, ...
x = 8 -3 = 5 . . . . lesser x
x = 8 +3 = 11 . . . greater x
Answer
It is $180
Step-by-step explanation:
You do 450 times 40% and you get $180
Combine like terms to get