QUESTION 18 18) Refer to the following problem to answer question 18, 19 & 20 The personnel director at a Wall Street brokerage house believes that executives working in the "Big Apple" tend to have higher IQ scores than the national executive mean IQ. The national mean IQ score for executives is 112 with a population standard deviation of 18. If a random sample of 81 "Big Apple" executives yields a mean IQ score of 116, do these sample results support the personnel director's claim at 1%? Determine the alternative hypothesis O a. Ha: u 112 O d. Ha: | # 112 QUESTION 19 19) Referring to problem 18, determine the z-score of the study result O a.+2 Ob.-2 O c. 1.5 O d. none of the choices QUESTION 20 20 ) Referring to question 18, what would the critical z-score for the decision rule be? O a.-2.33 Ob.+2.33 O c. 1.65 Od. +1.96