Answer:
The probability that exactly one switch is good is
Step-by-step explanation:
The probability that a switch is defective is:
The probability that a switch is not defective is
Therefore, if two switches are selected, the probability that exactly 1 is good is:
The marked angles are opposite angles, and as such they have the same measure. So, we have
Subtract 2a and 11 from both sides to get
Divide both sides by 4 to get
Now that we know the value of a, we can compute the measure of the angles. We can also verify that the solution we found is correct by verifying that both expressions actually give the same result: