Answer:
(a) [tex]P(Two\ Positive) = 0.2775[/tex]
(b) It is not too low
Step-by-step explanation:
Given
[tex]P(Single\ Positive) = 0.15[/tex]
[tex]n = 2[/tex]
Solving (a):
[tex]P(Two\ Positive)[/tex]
First, calculate the probability of single negative
[tex]P(Single\ Negative) =1 - P(Single\ Positive)[/tex] --- complement rule
[tex]P(Single\ Negative) =1 - 0.15[/tex]
[tex]P(Single\ Negative) =0.85[/tex]
The probability that two combined tests are negative is:
[tex]P(Two\ Negative) = P(Single\ Negative) *P(Single\ Negative)[/tex]
[tex]P(Two\ Negative) = 0.85 * 0.85[/tex]
[tex]P(Two\ Negative) = 0.7225[/tex]
Using the complement rule, we have:
[tex]P(Two\ Positive) = 1 - P(Two\ Negative)[/tex]
So, we have:
[tex]P(Two\ Positive) = 1 - 0.7225[/tex]
[tex]P(Two\ Positive) = 0.2775[/tex]
Solving (b): Is (a) low enough?
Generally, when a probability is less than or equal to 0.05; such probabilities are extremely not likely to occur
By comparison:
[tex]0.2775 > 0.05[/tex]
Hence, it is not too low