Final answer:
In a chi-square test, the usual level of significance is 0.05 or a = 0.05.
Step-by-step explanation:
In a chi-square test, the usual level of significance is 0.05 or a = 0.05. This means that there is a 5% chance of rejecting the null hypothesis when it is true. The level of significance represents the threshold at which we are willing to accept evidence against the null hypothesis.
For example, if the calculated chi-square test statistic is greater than the critical value at a significance level of 0.05, we would reject the null hypothesis. Conversely, if the calculated chi-square test statistic is less than or equal to the critical value at a significance level of 0.05, we would fail to reject the null hypothesis.
Therefore, the answer to the question is Option D. 0.10.