Answer:
There is a 99.99998% probability that at least one valve opens.
Step-by-step explanation:
For each valve there are only two possible outcomes. Either it opens on demand, or it does not. This means that we use the binomial probability distribution to solve this problem.
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 combinatios of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
In this problem we have that:

Calculate P(at least one valve opens).
This is 
Either no valves open, or at least one does. The sum of the probabilities of these events is decimal 1. So:


So


Finally

There is a 99.99998% probability that at least one valve opens.
Answer: 2x-y=15
Step-by-step explanation: can u be more detailin
Answer:
A) 150
Step-by-step explanation:
All the angles in a triangle must add up to a total of 180 degrees.
So we can make an equation as given below:
20+10+?=180
30+?=180
?=150
So the missing angle is 150 degrees
If we refer to the longest side as x and the shortest side as y and the medium side as z then we come up with this formation:
x+y+z= 22
y is shorter than x by 5 inches so y= x-5
z is longer than y by 2 inches therefore z= x-5 +2
therefore:
x+(x-5)+(x-5+2)=22
x+x-5+x-5+2=22
3x-8=22
3x= 22-8
3x=14
x=

replace x in y and z in previous formations