Answer:
(a) P (Both vehicles are available at a given time) = 0.81
(b) P (Neither vehicles are available at a given time) = 0.01
(c) P (At least one vehicle is available at a given time) = 0.99
Step-by-step explanation:
Let A = Vehicle 1 is available when needed and B = Vehicle 2 is available when needed.
<u>Given</u>:
The availability of one vehicle is independent of the availability of the other, i.e. P (A ∩ B) = P (A) × P (B)
P (A) = P (B) = 0.90
(a)
Compute the probability that both vehicles are available at a given time as follows:
P (Both vehicles are available) = P (Vehicle 1 is available) ×
P (Vehicle 2 is available)


Thus, the probability that both vehicles are available at a given time is 0.81.
(b)
Compute the probability that neither vehicles are available at a given time as follows:
P (Neither vehicles are available) = [1 - P (Vehicle 1 is available)] ×
[1 - P (Vehicle 2 is available)]
![P(A^{c}\cap B^{c})=[1-P(A)]\times [1-P(B)]\\](https://tex.z-dn.net/?f=P%28A%5E%7Bc%7D%5Ccap%20B%5E%7Bc%7D%29%3D%5B1-P%28A%29%5D%5Ctimes%20%5B1-P%28B%29%5D%5C%5C)

Thus, the probability that neither vehicles are available at a given time is 0.01.
(c)
Compute the probability that at least one vehicle is available at a given time as follows:
P (At least one vehicle is available) = 1 - P (None of the vehicles are available)
![=1-[P(A^{c})\times P(B^{c})]\\=1-0.01.....(from\ part\ (b))\\ =0.99](https://tex.z-dn.net/?f=%3D1-%5BP%28A%5E%7Bc%7D%29%5Ctimes%20P%28B%5E%7Bc%7D%29%5D%5C%5C%3D1-0.01.....%28from%5C%20part%5C%20%28b%29%29%5C%5C%20%20%3D0.99)
Thus, the probability that at least one vehicle is available at a given time is 0.99.