Tyesha found that the [tex]$z$[/tex]-statistic was 2.1 and that the critical [tex]$z$[/tex]-values were -1.96 and 1.96. Which of the following is a valid conclusion based on these results?

A. One can reject the null hypothesis.
B. One can reject the alternate hypothesis.
C. One can accept the null hypothesis.
D. One cannot accept or reject the null hypothesis.



Answer :

To determine the valid conclusion based on the given [tex]$z$[/tex]-statistic and the critical [tex]$z$[/tex]-values, we need to compare the calculated [tex]$z$[/tex]-statistic to the range defined by the critical [tex]$z$[/tex]-values. Here’s a detailed step-by-step explanation:

1. Understand the Hypotheses:
- The null hypothesis (H₀) is typically the hypothesis that there is no effect or no difference. It is what you seek to reject when performing a hypothesis test.
- The alternate hypothesis (H₁) is what you are looking to provide evidence for. It is usually that there is an effect or a difference.

2. Identify the [tex]$z$[/tex]-statistic:
- Tyesha’s calculated [tex]$z$[/tex]-statistic is [tex]\(2.1\)[/tex].

3. Identify the critical [tex]$z$[/tex]-values:
- The critical [tex]$z$[/tex]-values provided are [tex]\(-1.96\)[/tex] and [tex]\(1.96\)[/tex].

4. Define the Decision Rule:
- In hypothesis testing, we compare the [tex]$z$[/tex]-statistic to the critical [tex]$z$[/tex]-values to make a decision:
- If the [tex]$z$[/tex]-statistic is within the range defined by the critical values [tex]\([-1.96, 1.96]\)[/tex], we fail to reject the null hypothesis.
- If the [tex]$z$[/tex]-statistic is outside the range defined by the critical values, we reject the null hypothesis.

5. Compare the [tex]$z$[/tex]-statistic to the critical values:
- We need to check if [tex]\(2.1\)[/tex] falls within or outside the range [tex]\([-1.96, 1.96]\)[/tex].

6. Make the Decision:
- Since [tex]\(2.1\)[/tex] is greater than [tex]\(1.96\)[/tex] and does not lie within the range [tex]\([-1.96, 1.96]\)[/tex], we have:
- [tex]\(2.1 > 1.96\)[/tex] (outside the range)

7. Draw the Conclusion:
- Because the [tex]$z$[/tex]-statistic ([tex]\(2.1\)[/tex]) is outside the critical value range ([tex]\([-1.96, 1.96]\)[/tex]), we have sufficient evidence to reject the null hypothesis.

Therefore, the valid conclusion based on these results is:
One can reject the null hypothesis.