Answer:
becuae he couldent see sorry i had to do that
Answer:
predictive value of a positive test = 18.18%
predictive value of a negative test = 94.03%
Step-by-step explanation:
Sensitivity = 60% = 0.6
Specificity = 70% = 0.7
Let True Positive = TP
True Negative = TN
False Negative = FN
Prevalence = 10% = 0.1
Three hundred people are screened, 
Total number of people having the disease, 
But TP = 1.5 FN
30 = 1.5 FN + FN
30 = 2.5 FN
FN = 30/2.5
FN = 12
TP = 1.5 FN = 1.5 * 12
TP = 18
81 + TN = 270
TN = 189
To calculate the Predictive value of positive test (PPT)
To calculate the Predictive value of negative test (PNT)
A - 1.2b = - 3 ⇒ eq. 1
0.2b + 0.6a = 12 ⇒ eq. 2
a - 1.2b = - 3
a = 1.2b - 3 ⇒ eq. 3
Substitute eq. 3 to eq. 2
0.2b + 0.6(1.2b - 3) = 12
0.2b + .72b - 1.8 = 12
Combine like terms
0.92b = 12 + 1.8
0.92b = 13.8 ⇒ divide both sides by 0.92 to get the value of b
<span>b = 15
</span>Substitute the value of b to eq. 3
a = 1.2b - 3
a = 1.2(15) - 3
<span>a = 15
</span>to check: substitute the values of a and b to:
eq. 1
a - 1.2b = - 3
15 - (1.2)(15) = -3
15 - 18 = - 3
- 3 = -3 ⇒ correct!
eq. 2
0.2b + 0.6a = 12
(0.2)(15) + (0.6)(15) = 12
3 + 9 = 12
12 = 12 ⇒ correct!
Using it's concept, the probabilities are given as follows:
a) C. 7/20.
b) D. 15/22.
<h3>What is a probability?</h3>
A probability is given by the <u>number of desired outcomes divided by the number of total outcomes</u>.
For item a, we have that there are 60 students with no curfew, and of those, 21 have no chores, hence the probability is given by:
p = 21/60 = 7/20
Which means that option C is correct.
For item b, we have that there are 66 students with no shores, and of those, 45 have a curfew, hence the probability is given by:
p = 45/66 = 15/22
Which means that option D is correct.
More can be learned about probabilities at brainly.com/question/14398287
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