A random sample of 102 lightning flashes in a certain region resulted in a sample average radar echo duration of 0.86 sec and a sample standard deviation of 0.35 sec. Calculate a 99% (two-sided) confidence interval for the true average echo duration μ.

99% Confidence interval:  (0.77,0.95)

Step-by-step explanation:

We are given the following in the question:

Sample mean, = 0.86 sec

Sample size, n = 102

Alpha, α = 0.01

Sample standard deviation, s = 0.35 sec

Degree of freedom =

99% Confidence interval:  

Putting the values, we get,  

(0.77,0.95) is the required 99% confidence interval for the true average echo duration μ.

assuming you mean addition: addition and subtraction are reverse operations.

step-by-step explanation: