Which t distribution is more similar to standard normal distribution?

t distribution with 1 degrees of freedom

t distribution with 20 degrees of freedom

t distribution with 10 degrees of freedom

t distribution with 100 degrees of freedom

We take samples with a size of 550 from an exponential distribution. What is an approximate distribution for the sample means?

Unknown

Normal

Uniform

Exponential

___________ is based on dividing a population into subgroups, sampling a set of subgroups, and conducting a complete census within the subgroups sampled.

Stratified sampling

Continuous process sampling

Systematic sampling

Cluster sampling

The historical data of Velvetta Inc., a healthcare products manufacturer, has shown that in a production process for filling bottles of shampoo, variance in the volume is constant; however, clogs in the filling machine often affect the mean volume. The historicalpopulation standard deviation is 3milliliters. In filling 250-milliliter bottles, asample of 15found a mean volume of 247 milliliters.

How much is themargin of errorfor a 95% confidence interval for the sample mean?

Show your answer with2 decimals.

Purchase amounts in a store are normally distributed with a mean of $200 and a standard deviation of $80.

If we take a sample of 100 purchases, what is the probability that theaverage purchaseis greater than 209?

Provide your answer as a number between 0 and 1 with2 decimals.

In a big corporation, we have taken a sample of 20 employees, and 8 of them have a graduate degree (so, the sample proportion is 8/20). Find theupper boundof an80%confidence interval for the proportion of employees with a graduate degree.

Provide your answer as a number between 0 and 1 with2 decimals.