a researcher wants to know the typing speed of the students in a large vocational school. the population standard deviation is previously known to be 2.5 minutes. if the researcher wants a margin of error of 0.50 minute and an alpha level of 0.05, what should be the sample size?

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:

Ive seen this before! the answer is b