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: