The t distribution should be used whenever a. the sample size is ...

[Jipu 123]

The t distribution should be used whenever
 a. the sample size is less than 30.
  b. the sample standard deviation is used to estimate the population standard deviation.
   c. the population is not normally distributed.
  d. the population standard deviation is known.

Question 2

The president of a company wants to see if the new anti-smoking campaign is having any influence on his employees. A sample of 100 employees who smoked prior to the campaign is taken. Thirty-six employees said they smoked less, 15 employees said they smoked more, and 49 employees said there was no change.
 a. State the null and alternative hypotheses.
  b. Test the null hypothesis at the 1 level of significance.

[qytan]

Answer to Question 1

b

Answer to Question 2

a. H0: p = .5
Ha: p  .5
b. z = 2.80; p-value = .0052; reject the null hypothesis; there is a significant difference.

[Jipu 123]

Gracias!

[okolip]

Excellent