Answer:
The correct answer is option 'a' : 120 is more than 2.5 standard deviations above the expected value.
Step-by-step explanation:
For an exponential distribution we have
The expected value μ = 80
No of trails n = 200
Thus we have
The deviation is related to expected value and probability as
Thus the values between the given deviation is
Now since 120 successes are out of the range of [62.75,97.25] thus 120 is more than the expected value.