The weekly extracurricular sports time (in hours) for two students, A and B, over 16 weeks is shown in the stem-and-leaf plot below:

\begin{center}
\begin{tabular}{ r r | r | l }
\multicolumn{1}{c|}{A} &  & \multicolumn{1}{|c}{B} &  \\
\hline
6 & 1 & 5. &  \\
8530 & 6. & 3 &  \\
7532 & 7. & 46 &  \\
6421 & 8. & 12256666 &  \\
 & 42 & 9. & 0238 \\
 &  & 10. & 1 \\
\end{tabular}
\end{center}

Which of the following conclusions is incorrect?

A. The sample median of A's weekly extracurricular sports time is 7.4

B. The sample mean of B's weekly extracurricular sports time is greater than 8

C. The estimated probability that A's weekly extracurricular sports time exceeds 8 hours is greater than 0.4

D. The estimated probability that B's weekly extracurricular sports time exceeds 8 hours is greater than 0.6