Respuesta :
Answer:
(i) [tex]\frac {4}{15}[/tex]
(ii) [tex]\frac 1 3[/tex]
(iii) [tex]\frac 2 3[/tex]
(iv) [tex]\frac 3 4[/tex]
Step-by-step explanation:
Let [tex]A[/tex] be the event that the dog has gone home,
[tex]B[/tex] be the event that the dog has gone to the picnic area, and
[tex]C[/tex] be the event that the dog has gone to the park.
Assuming all the three events are equally likely to happen, so,
[tex]P(A)=P(B)=P(C)=\frac 1 3\;\cdots (1)[/tex]
Now, let [tex]F[/tex] and [tex]L[/tex] bet the event of found and lost of the dog.
Given that the chances of finding the dos are [tex]80\%[/tex] and [tex]40\%[/tex], if the dog is in the picnic area and woods respectively.i.e
[tex]P\left(\frac {F}{B}\right)=0.8\;\cdots (2)[/tex],
[tex]P\left(\frac {L}{B}\right)=1-0.8=0.2\;\cdots (3)[/tex] and
[tex]P\left(\frac {F}{C}\right)=0.4\;\cdots (4)[/tex]
[tex]P\left(\frac {F}{C}\right)=1-0.4=0.6\;\cdots (5)[/tex]
(i) The probability that the dog will be found in the park
[tex]=[/tex] Probability of going the dog to park [tex]\times[/tex] Probability of found in the park
[tex]=P(B)\timesP\left(\frac {F}{B}\right)[/tex] [using equations (1) and (2)]
[tex]=\frac 1 3 \times 0.8[/tex]
[tex]=\frac {4}{15}[/tex]
(ii) If the dog is in home, the chance of finding the dog is 100%.
So, the probability that the dog will be found at home
[tex]=[/tex] The probability that the dog has gone home
[tex]=P(A)[/tex]
[tex]=\frac 1 3[/tex] [ from equation (1)]
(iii) Given that the dog is found in the park, so, the probability of founding the dog in the picnic area of the park
[tex]=\frac {P(B)\timesP\left(\frac {F}{B}\right)}{P(B)\timesP\left(\frac {F}{B}\right)+P(C)\timesP\left(\frac {F}{C}\right)}[/tex]
[tex]=\frac {\frac 1 3\times0.8}{\frac 1 3\times0.8+\frac 1 3\times0.4}[/tex] [using equations (1), (2) and (4)]
[tex]=\frac 2 3[/tex]
(iv) Given that the dog is lost, so, the probability of losing the dog in the woods
[tex]=\frac {P(C)\timesP\left(\frac {L}{C}\right)}{P(B)\timesP\left(\frac {L}{B}\right)+P(C)\timesP\left(\frac {L}{C}\right)+P(A)\timesP\left(\frac {L}{A}\right)}[/tex]
[tex]=\frac {\frac 1 3\times0.6}{\frac 1 3\times0.2+\frac 1 3\times0.6+\frac 1 3 \times 0}[/tex] [using equations (1), (3) and (5)]
[tex]=\frac 3 4[/tex] .