Answer:
An 80% confidence intervals are (5.73 ,5.88)
Step-by-step explanation:
Given sample size (n) is = 270
The average score (μ) =5.81
and standard deviation σ= 0.99.
<u>80% confidence interval</u>:-
The<u> </u>80% confidence interval of the z- value is 1.28 ( from z-table)
An 80% confidence interval is defined by sample mean ± 1.28 standard error
that is μ ± 1.28 σ/√n
now substitute values (5.81 ± 1.28(0.99/√270))
(5.81 - 1.28(0.0602),5.81 + 1.28(0.0602)
(5.81 -0.0770 ,5.81 -0.0770)
(5.73 ,5.88)
<u>Conclusion:</u>-
An 80% confidence intervals are (5.73 ,5.88)
Therefore the population mean 5.81 lies between (5.73 ,5.88) at 80% confidence intervals
