The national average for the number of students per teacher for all US public schools is 16.1. A random sample of 12 school districts from a moderately populated area showed that the mean number of students per teacher was 18.2 with a variance of 4.41. Estimate the true mean number of students per teacher with 95% confidence. Put answers in the form: (lower,upper) & to 2 decimal places. How does your estimate compare with the national average?
sample mean 'x̄= | 18.200 |
sample size n= | 12.00 |
sample std deviation s= | 2.1000 |
std error 'sx=s/√n= | 0.6062 |
for 95% CI; and 11 df, value of t= | 2.201 | |
margin of error E=t*std error = | 1.334 | |
lower bound=sample mean-E = | 16.866 | |
Upper bound=sample mean+E = | 19.534 | |
from above 95% confidence interval for population mean =(16.87,19.53) |
our confidence interval has all values above the national average value of 16.1.
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