We're building a 95% confidence interval for the average length of a potato. The standard deviation for a potato is 1 inch. We measure 40 potatoes and findx=3.4 inches. What is the lower bound of our confidence interval?

3.09 inches

4.12 inches

1.96 inches

2.87 inches

When using a t table, the number of degrees of freedom is always:

one less than the sample mean.

less than 30.

one more than the sample size.

one less than the sample size.

I want to know if smoking during pregnancy delays language acquisition. Children of mothers who do not smoke during pregnancy typically say their first word at 11 months of age. We will contact mothers who used tobacco during pregnancy to ask when their child said their first word. Our null hypothesis will be:

>11

<11

=11

=11

If the null hypothesis were true, data like mine would only occur in 6% of trials. 6% is my:

population proportion.

p-value.

correlation coefficient.

sample proportion

When can I not use a central limit theorem?

I want a population proportion. My sample proportion is 65% and n = 20.

I want a population proportion. My sample has 6 successes and 4 failures.

I want a population mean. My data (n = 8) is normally distributed.

I want a population mean. My data (n = 63) is not normally distributed.