6. (10 points) Jiajia and Junjun are having a bike race. At the start, Jiajia's speed is 7 meters/second, and then her speed increases by 1 meter/second every 10 seconds. At the start, Junjun's speed is 1 meter/second, and then his speed doubles every 10 seconds. Both start from the starting point at the same time and arrive at the finish line at the same time. Therefore, the total length of the race is ( ) meters.
A. 450
B. 524
C. 534
D. 570
【Answer】List as follows:
\begin{tabular}{|c|c|c|c|c|c|}
\hline 10 seconds & \multicolumn{2}{|c|}{ Jiajia } & \multicolumn{2}{|c|}{ Junjun } & Their distance \\
\hline & Speed & Distance & Speed & \begin{tabular}{l} 
Dis \\
tance
\end{tabular} & \\
\hline First & 7 & 70 & 1 & 10 & \begin{tabular}{l} 
(7-1) $\times 10=60$ distance \\
increased
\end{tabular} \\
\hline Second & 8 & 80 & 2 & 20 & $(8-2) \times 10=60$ distance increased \\
\hline Third & 9 & 90 & 4 & 40 & $(9-4) \times 10=50$ distance increased \\
\hline Fourth & 10 & 100 & 8 & 80 & \begin{tabular}{l}
$(10-8) \times 10=20$ distance in \\
creased
\end{tabular} \\
\hline
\end{tabular}
\begin{tabular}{|l|l|l|l|l|c|}
\hline Fifth & 11 & 110 & 16 & 160 & \begin{tabular}{c}
$(16-11) \times 10=50$ distance de \\
creased
\end{tabular} \\
\hline \begin{tabular}{r} 
Sixth \\
(7th \\
second)
\end{tabular} & 12 & 84 & 32 & 224 at this point 140 apart, catch-up time 7 seconds \\
(accelerated to catch up just in time)
\end{tabular}
$(60+60+50+20-50) \div(32-12)=140 \div 20=7$ (seconds)
$12 \times 7=84$
$70+80+90+100+110+84=534$ (meters)
Therefore, the answer is: $C$.