The equation 7×+1=4×+10 ?
2 answers:
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Answer:
a) The 95% confidence interval for the true mean is:
b) This margin of error can be achieved with a sample of size 27 individuals.
Step-by-step explanation:
a) We have to construct a 95% confidence interval for the populations mean WBC.
The sample results, from a sample size n=187, are:
- Sample mean: 8.636
- Standard deviation: 3.9265
As we are using the sample standard deviation to estimate the population standard deviation, we will use the t-statistic.
The degrees of freedom are:
The t-statistic for a 95% interval and 186 degrees of freedom is t=1.9728.
Now, we can calculate the margin of error of the confidence interval:
The upper and lower bound of the confidence interval are:
The 95% confidence interval for the true mean is:
b) As the confidence level is equal, the t-value is the same.
But the sample size has to be adjusted to have an margin of error of +/-1.5.
We use the formula for the margin of error:
This margin of error can be achieved with a sample of size 27 individuals.