Chapter 12 Questions

Complete the following questions. The questions may include pictures or graphics to illustrate or aid in solving the problem. You can check your answer by clicking View Answer. If the question is unclear, confusing, or if you need further clarification, send me an email.

1.  Given that the average IQ in the population is 100 and that the standard deviation is 15, is the sample of statisticians whose IQs are given below different from the population?

Answer

Looking this up on the z-table, we see that the likelihood of a z-score of 4.08 or greater is less than .025 (it's a two-tailed test). Therefore we reject the null hypothesis and conclude this is a significant difference.

2.  Imagine that we thought the statisticians in the above sample were more intelligent than BYU students, whose average IQ is 110 and whose standard deviation is 20. Are the statisticians more intelligent than the average BYU student?

Answer

Looking this up on the z-table, we see that the likelihood of a z-score of 1.837 or greater is less than .05 (it's a one-tailed test). Therefore we conclude the statisticians are more intelligent than the average BYU student.

3.  Now, imagine the same situation as in question two. In this case, however, we do not know the BYU standard deviation. Are the statisticians more intelligent than the average BYU student?

Answer

Looking this up on the t-table at the .05 level, one-tailed, we reject the null hypothesis and conclude that the statisticians are more intelligent than the average BYU student.

4.  Given the above sample of statisticians, between what two scores will 95% of all statisticians' IQs fall?

Answer

5.  Given the above sample of statisticians, between what two scores will 99% of all statisticians' IQs fall?

Answer