Answer:
i thank it is 25 seconds.
Step-by-step explanation:
Mistake on my part ignore this
Answer with Step-by-step explanation:
Since the given event is binary we can use Bernoulli's probability to sove the problem
Thus for an event 'E' with probability of success 'p' the probability that the event occurs 'r' times in 'n' trails is given by

Part a)
For part a n = 11 , r =9, p = 0.75
Applying values we get

Part b)
For part b n = 20 , r = 16 , p=0.75
Applying values we get
