Answer:
135 to 143 minutes.
Step-by-step explanation:
Standard deviation (s) = 22.6 minutes
Sample size (n) = 123
Sample average (X) = 139 minutes
The lower and upper bounds of a confidence interval are given by:
Lower bound:
Upper bound:
For a confidence interval of 95%, the z-score value is 1.96.
Therefore, the 95% confidence interval for the mean surgery time is:
Lower bound:
Upper bound:
The 95% confidence interval is 135 to 143 minutes.
Answer:
I think the answer is 4.5 pi meters
If his water to cement ratio is 20 to 30, this means that if he uses 20 liters of water, he'd use 30 liters of cement.
The total mixture would then be 20+30=50 liters.
and the water would be 20/50=0.4 or 40% of the total mixture.
The factors of 9 are 1, 3, and 9