In: Statistics and Probability
The standard deviation of the population of airline departure delays is σ = 23 minutes. Suppose that we choose an SRS of 152 departures. Calculate the standard deviation of their mean length in minutes. Then apply the Central Limit Theorem and the 68-95-99.7 Rule to complete the following statement: “about 95% of all samples will have its mean within ± ________ minutes of the true population mean μ.”
Round your answer to 2 decimal places of accuracy.
Solution :
Given that
standard deviation =
= 23
n = 152
=
/
n = 23 /
152 = 1.87
P(
- 2
<
<
+ 2
) = 95%
=
±
2
= 95%
= ±
2 * 1.87 = 95%
=
±
3.74 = 95%
“about 95% of all samples will have its mean within ± 3.74 minutes of the true population mean μ.”