Answer:
Part a : 0.002744
Part b : 0.997256
Explanation:
The probability that a specific engine is available when needed is 0.86.
So, The probability that fire engine will not be available when needed =

(a)
The probability that no fire engine is available when needed =

= 0.002744
(b)
p(at least one available) =

= 0.997256