Answer:
The correct answer is "771.44; 779.16".
Explanation:
Given:
Number of samples,
Mean,
Standard deviation,
At 90% confidence interval,
From normal distribution at 90% confidence level,
Now,
Margin of error will be:
⇒
By substituting the values, we get
hence,
The mean at 90% CI will be:
=
=
=