To solve the problem, we are given:

Equation:

$53.715 + 51.3 + 52.62 + n = 210$

Here, $n$ is the time in seconds that the 4th runner must complete their segment for the team to meet the goal of 210 seconds.

Step 1: Add the times for the first three runners

$53.715 + 51.3 + 52.62 = 157.635$

Step 2: Subtract the sum from the total time

$n = 210 - 157.635$

Step 3: Simplify

$n = 52.365$

Final Answer:

The 4th runner must complete their segment in 52.365 seconds for the team to meet its goal.

Would you like more details or clarifications on this? Here are 5 related questions for deeper understanding:

1. How can this approach be generalized to solve similar problems in relay races?
2. What strategies might the 4th runner use to achieve a target time like this?
3. How can the total time of 210 seconds be split more evenly among runners for better results?
4. If one runner were slower, how would this impact the 4th runner's required time?
5. How does this type of calculation apply to other team-based sports or activities?

Tip: In problems involving summation equations, always isolate the unknown variable by moving all known values to the other side of the equation systematically.