Answer: [tex]z_{\text{calc}}=-0.32[/tex]
Explanation:
The test statistic for difference of two population means :-
[tex]z=\dfrac{\mu_1-\mu_2}{\sigma\sqrt{\dfrac{1}{n_1}+\dfrac{1}{n_2}}}[/tex]
Given : [tex]\sigma=\sigma_1=\sigma_2=3[/tex]
[tex]n_1 = n_2 = 20[/tex]
[tex]\mu_1=23.7[/tex]
[tex]\mu_2=24[/tex]
Then , [tex]z=\dfrac{23.7-24}{(3)\sqrt{\dfrac{1}{20}+\dfrac{1}{20}}}[/tex]
[tex]\Rightarrow\ z=-0.316227766017\approx-0.32[/tex]
Hence, the value of [tex]z_{\text{calc}}=-0.32[/tex]