Question

Based on the information given for each of the following studies, decide whether to reject the null hypothesis. For each, give (a) the Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected, (b) the Z-score on the comparison distribution for the sample score, and (c) your decision. Assume that all populations are normally distributed. Use the space provided to show your computations, and summarize all the answers in the table given below.

Study	μ	σ	Sample Score	p	Tails of Test
A	100.0	10.0	80	0.05	1 (low predicted)
B	100.0	20.0	80	0.01	2
C	74.3	11.8	80	0.01	2
D	16.9	1.2	80	0.05	1 (low predicted)
E	88.1	12.7	80	0.05	2

Study	Z-score of cut off(s)	Z-score of sample	Decision
A
B
C
D
E

Answer 1

Z score cut off are obtained from the normal table (Z_c)

Z score is calculated using formula

Decision: Reject the null hypothesis if |Z_c| < |Z| ( for 1 tail )

and Reject the null hypothesis if Z_c < |Z| ( for 2 tail )

Study	Z-score of cut off(s)	Z-score of sample	Decision
A	-1.645		Reject
B	2.58		Accept
C	2.58		Accept
D	-1.645		Reject
E	1.96		Accept