Answer:
a) 0.2416
b) 0.4172
c) 0.0253
Step-by-step explanation:
Since the result of the test should be independent of the time , then the that the test number of times that test proves correct is independent of the days the river is correct .
denoting event a A=the test proves correct and B=the river is polluted
a) the test indicates pollution when
- the river is polluted and the test is correct
- the river is not polluted and the test fails
then
P(test indicates pollution)= P(A)*P(B)+ (1-P(A))*(1-P(B)) = 0.12*0.84+0.88*0.16 = 0.2416
b) according to Bayes
P(A∩B)= P(A/B)*P(B) → P(A/B)=P(A∩B)/P(B)
then
P(pollution exists/test indicates pollution)=P(A∩B)/P(B) = 0.84*0.12 / 0.2416 = 0.4172
c) since
P(test indicates no pollution)= P(A)*(1-P(B))+ (1-P(A))*P(B) = 0.84*0.88+ 0.16*0.12 = 0.7584
the rate of false positives is
P(river is polluted/test indicates no pollution) = 0.12*0.16 / 0.7584 = 0.0253
Answer:
3/10
Step-by-step explanation:
Just multiply all of the numerators (top numbers) and then multiple all of the denominators (bottom numbers)
2/3x3/4x3/5 would be 18/60 Then take any number that is a factor to both 18 and 60 and divide both numbers by that factor. I could use 2 or 3 or 6 because both 18 and 60 is divisible by any of these numbers. I will choose 3. I will divide the top and bottom of 18/60 by 3 to get 6/20, now I will divide the top and bottom of that number by 2 to get 3/10
<em>3/4 is the total.</em>
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<em>See attached image for explanation.</em>
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<em>Please consider marking "Brainliest". </em>
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<em>Thanks <3</em>
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When solving these proportions we just remember when moving a number from one side to the other if it started in the numerator it ends up in the denominator and vice versa.
I'll do it in two steps here for teaching purposes; it's not too hard to go directly to the answer.
