In a randomized comparative experiment on the effect of color on the performance of a cognitive task, researchers randomly divided 69 subjects (31 males and 38 females ranging in age from 17 to 25 years) into three groups. Participants were asked to solve a series of 6 anagrams. One group was presented with the anagrams on a blue screen; one group saw them on a red screen; and one group had a neutral screen. The time, in seconds, taken to solve the anagrams was recorded. The paper reporting the study gives x⎯⎯⎯=11.5 and s=4.4 for the times of the n= 21 members of the neutral group.
A. Give a 95% confidence interval for the mean time in the population from which the subjects were recruited. B. What conditions for the population and the study design are required by the procedure you used?
C. Which of these conditions are important for the validity of the procedure in this case?

Anormally distributed data set has a mean of 176.3 and a standard deviation of 4.2. what is the approximate z-score for the data value of 167.9? 2.00 −2.00 8.4 −8.4

Which scenarios are most effectively explored by conducting an experiment? there is more than one correct answer. select all that apply. researchers want to study the effectiveness of a particular drug for treating migraines. they want to know which dosage of the drug yields the best results with the least side effects. to ensure fair results, the researchers want to ensure that participants and dosage administrators do not know which dosage participants receive. a teacher wants to plan a class fieldtrip and quickly determine where students prefer to go for the class fieldtrip. a car mechanic wants to know which of two engine brands makes better-performing engines. he wants to test the engines in identical situations and rate their performance in a way that can be fairly measured. a chemist studies the properties of a metal compound. she wants to know how the sample size of the metal affects its ability to conduct electricity. she wants to conduct the research in a controlled environment to minimize bias. a realty company wants to know the average income of its clients. the company wants to gather data income from current clients.

Triangle abc has side lengths: ab = 3.5  cm, bc = 2.4 cm, and ac = 4.2 cmδabc ≅ δhjkwhat is the length of side hj?