Question

INFERENCES ABOUT THE POPULATION MEAN
DISTINGUISH BETWEEN Z-TEST AND T-TEST.

1. A GROUP OF 9 STORE MANAGERS WAS DRAWN FOR ANALYSIS OF THEIR IQ SCORES. ASSUME THAT INDIVIDUAL SCORES ARE NORMALLY DISTRIBUTED, WITH THE UNKNOWN POPULATION AVERAGE AND POPULATION STANDARD DEVIATION OF 15. SAMPLE SUMMARIES WERE:

(SAMPLE MEAN) = 88.2 AND (SAMPLE STANDARD DEVIATION) = 12.

(A) AT THE 1% SIGNIFICANCE LEVEL, DO WE HAVE SUFFICIENT EVIDENCE THAT THE POPULATION AVERAGE IQ WAS BELOW 100?
CIRCLE ONE: YES! || NO! (ANSWER IS YES)

(B) SHOW THE TEST STATISTIC VALUE, THE CRITICAL VALUE(S) NEEDED FOR YOUR DECISION AND FORMULATE THE REJECTION RULE.

NULL HYPOTHESIS STATES:

ALTERNATIVE HYPOTHESIS STATES:

TEST STATISTIC =

CRITICAL VALUE =

REJECTION RULE STATES: REJECT THE NULL HYPOTHESIS IF  <FILL THE BLANK SPACE>

DECISION: WE (REJECT) (DO NOT REJECT) THE NULL HYPOTHESIS (CIRCLE ONE ANSWER)

(C) ESTIMATE THE POPULATION AVERAGE IQ SCORE WITH THE 95% CONFIDENCE. (SHOW THE DETAILED ANSWERS, PLEASE!)

CRITICAL VALUE =

MID-POINT =

MARGIN OF ERROR =

UPPER CONFIDENCE LIMIT =

LOWER CONFIDENCE LIMIT =

WIDTH OF THE INTERVAL =

Answer 1