Answer:
c) ![\simeq 0.2438](https://tex.z-dn.net/?f=%5Csimeq%200.2438)
Step-by-step explanation:
Rate of collision,
1.2 collisions every 4 months
or,
= 0.3 collisions per month
So, the Poisson distribution for the random variable no. of collisions per month (X) is given by,
P(X =x) = ![\frac{e^{-\lambda}\times {\lambda}^{x}}}{x!} ](https://tex.z-dn.net/?f=%5Cfrac%7Be%5E%7B-%5Clambda%7D%5Ctimes%20%7B%5Clambda%7D%5E%7Bx%7D%7D%7D%7Bx%21%7D%0A)
for x ∈ N ∪ {0}
= 0 otherwise --------------------------------------(1)
here,
collision / month
No collision over a 4 month period means no collision per month or X =0
Putting X = 0 in (1) we get,
P(X = 0) = ![\frac{e^{-0.3}\times {\0.3}^{0}}{0!} ](https://tex.z-dn.net/?f=%5Cfrac%7Be%5E%7B-0.3%7D%5Ctimes%20%7B%5C0.3%7D%5E%7B0%7D%7D%7B0%21%7D%0A)
------------------------------------(2)
Now, since we are calculating this for 4 months,
so, P(No collision in 4 month period)
=![0.7408182207^{4}](https://tex.z-dn.net/?f=0.7408182207%5E%7B4%7D)
-----------------------------------------------------------(3)
2 collision in 2 month period means 1 collision per month or X =1
Putting X =1 in (1) we get,
P(X =1) = ![\frac{e^{-0.3}\times {\0.3}^{1}}{1!} ](https://tex.z-dn.net/?f=%5Cfrac%7Be%5E%7B-0.3%7D%5Ctimes%20%7B%5C0.3%7D%5E%7B1%7D%7D%7B1%21%7D%0A)
------------------------------------(4)
Now, since we are calculating this for 2 months, so ,
P(2 collisions in 2 month period)
=![0.2222454662^{2}](https://tex.z-dn.net/?f=0.2222454662%5E%7B2%7D)
-----------------------------------------(5)
1 collision in 6 months period means
collision per month
Now, P(1 collision in 6 months period)
= P( X = 1/6] (which is to be estimated)
=![\frac {P(X=0)\times 5 + P(X =1)\times 1}{6}](https://tex.z-dn.net/?f=%5Cfrac%20%7BP%28X%3D0%29%5Ctimes%205%20%2B%20P%28X%20%3D1%29%5Ctimes%201%7D%7B6%7D)
= \frac {0.7408182207 \times 5 + 0.2222454662 \times 1}{6}[/tex]
-------------------------------------------(6)
So,
P(1 collision in 6 month period)
= ![0.6543894283^{6}](https://tex.z-dn.net/?f=0.6543894283%5E%7B6%7D)
------------------------------------------------(7)
So,
P(No collision in 6 months period)
= ![(P(X =0)^{6}](https://tex.z-dn.net/?f=%28P%28X%20%3D0%29%5E%7B6%7D)
---------------------------------(8)
so,
P(1 or fewer collision in 6 months period)
= (8) + (7 ) = 0.0785267444 +0.1652988882
---------------------------------------------(9)