Answer: The required probability is 0.6.
Step-by-step explanation:
Since we have given that
It is uniformly distributed between 40 minutes and 90 minutes,
Probability that her trip will take longer than 60 minutes would be
here, a = 40, b = 90, α = 60
Hence, the required probability is 0.6.
You would need 24 machines
Because 1 machine makes 5 envelopes per minute so simultaneously 24 machines can make 120 envelopes per minute.