Find the appropriate t-distribution value for the following confidence intervals:

1. 90% confidence, n is 24: Answer=

2. 95% confidence, n is 16: Answer =

3. 98% confidence, n is 26: Answer =

If the sample size was 14, and the t-value was 1.771, what is the correct confidence interval?

City planners would like to know the average income in Red Deer and would like to conduct a sample to collect this information. The sample data surveyed 256 households which revealed a sample mean of $85,000. The population standard deviation is known to be $13,200.

a) What is the standard error ofthemean?

b) At the 95% confidence level, what is the margin of error?

c) What is the upper limit in the interval?

d) What is the lowerlimitin the interval?