1) It is known that a laboratory task takes the average person 2.5 seconds. A researcher was interested in whether older people are slower (take longer) on this task. The researcher tested 30 randomly selected 80-year-olds. Their mean time was 2.7 seconds, with an estimated population standard deviation of 1.4 seconds. What should the researcher conclude (use the .05 level)?
a. /2 Identify the populations involved:
population 1 = _____________________________________________________________________
population 2 = _____________________________________________________________________
b. /2 State the research and null hypothesis:
Research Hypothesis = _____________________________________________________________
Null Hypothesis = _________________________________________________________________
c. /6 Determine the characteristics of the comparison distribution (hint: it is a distribution of means):
mean of the distribution of means =
degrees of freedom =
estimated population variance =
estimated population standard deviation =
variance of the distribution of means =
standard deviation of distribution of means =
d. /1 Cutoff sample score on the comparison distribution at which we’ll reject H0 (hint: 1 or 2 tails?) =
e. /1 Determine your sample’s score on the comparison distribution =
f. /1 Accept or reject the null hypothesis?
g. /4 Sketch the distributions involved:
