For parts $\mathbf{a}$ and $\mathbf{b}$, use technology to estimate the following.
a) The critical value of $t$ for a $98 \%$ confidence interval with $\mathrm{df}=10$.
b) The critical value of $t$ for a $99 \%$ confidence interval with $\mathrm{df}=104$.
a) What is the critical value of $t$ for a $98 \%$ confidence interval with $d f=10$ ?
2.76 (Round to two decimal places as needed.)
b) What is the critical value of $t$ for a $99 \%$ confidence interval with $\mathrm{df}=104$ ?
(Round to two decimal places as needed.)

Step 1 ：The problem is asking for the critical value of t for a given confidence interval and degrees of freedom. The critical value of t is the value that separates the region where the null hypothesis is rejected from the region where it is not rejected. It can be found using the t-distribution table or using a statistical software.

Step 2 ：For part a, the confidence level is 98% or 0.98 and the degrees of freedom is 10.

Step 3 ：For part b, the confidence level is 99% or 0.99 and the degrees of freedom is 104.

Step 4 ：Using a statistical software, we find that the critical value of t for a 98% confidence interval with df=10 is approximately 2.76, and the critical value of t for a 99% confidence interval with df=104 is approximately 2.62. These values are rounded to two decimal places as needed.

Step 5 ：Final Answer: For a 98% confidence interval with df=10, the critical value of t is approximately \(\boxed{2.76}\). For a 99% confidence interval with df=104, the critical value of t is approximately \(\boxed{2.62}\).