Answer:
And tha's equivalent to use this formula:
Step-by-step explanation:
For this case the 95%of the values are between the following two values:
(75 , 163)
And for this case we know that the variable of interest X "length of a movie" follows a normal distribution:
We can estimate the true mean with the following formula:
Now we know that in the normal standard distribution we know that we have 95% of the values between 1.96 deviations from the mean. We can find the value of the deviation with this formula:
And tha's equivalent to use this formula: