Question

Hypothesis Tests with Z-statistics

Students in a physics class have an average of 73 on exams with a standard deviation of 12. The teacher is testing a whether having open book exams will help her students get better scores. After 6 open book exams, her class has an average of 76.5 on the exams.

a. Who are the groups being compared/tested?
b. What are the null and research hypotheses?
c. what are the numbers needed for the z statistic?
d. What is the z statistic?
e. For a two tailed test at .05 significance, the critical area is +/- 1.96. What decision do we make?

Answer 1

Solution :

= 73

=76.5

=12

n = 6

a)This is the two tailed test .

b)The null and alternative hypothesis is ,

H0 :    = 73

Ha :     73

c)Test statistic = z

= ( - ) / / n

= (76.5 -73) / 12 / 6

d) z= 0.714

P(z >0.714 ) = 1 - P(z < 0.714) = 0.4752

P-value =0.4752

= 0.05  

the critical value for a two-tailed test is zc​=1.96.

z=0.714 ≤ zc​=1.96

0.4752< 0.05

Do not reject the null hypothesis .

There is insufficient evidence to suggest that