Answer:
The minimum sample size required to construct a 95% confidence interval for the population mean is 65.
Step-by-step explanation:
We are given the following in the question:
Population standard deviation,
We need to construct a 95% confidence interval such that the estimate is within 0.75 milligrams of the population mean.
Thus, the margin of error must me 0.75
Formula for margin of error:
Putting values, we get,
Thus, the minimum sample size required to construct a 95% confidence interval for the population mean is 65.
It equals 99. 4 times 9 equals 36. 11 times 9 equals 99.
Answer:
We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.
Step-by-step explanation:
For this case we are interesting in the parameter of the true proportion of people satisfied with the quality of education the students receive
The confidence level is given 95%, the significance level would be given by 
and 
. And the critical values are:
The estimated proportion of people satisfied with the quality of education the students receive is given by:
The confidence interval for the proportion if interest is given by the following formula:
And replacing the info given we got:
We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.
