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
Number of milk cartons put out for breakfast = 100
Number of cartons remaining at the end = 27
Number of cartons consumed = 100 - 27 = 73
Ratio of cartons remaining / cartons consumed = 27/73
Hope this helps!
Sorry the writing is really bad looking its hard to write on a laptop.
Answer:
0.08065
Step-by-step explanation:
Given that in a recent study,1 2006 randomly selected US adults (age 18 or older) were asked to give the number of people in the last six months with whom you discussed matters that are important to you.
If X is random variable then X has mean 2.2 and s = 1.4
n=2006
Std error of mean =
For 99% since sample size is large, t and z distn almost coincide.
Hence we can take 2.58 as critical value
Margin of error at 99% =
