To determine how long it took Jimmy to run from mile marker 1 to mile marker 4, we simply need to add the times for each segment of his run:

1. Jimmy took 7 minutes to run from mile marker 1 to mile marker 2.
2. Jimmy took 18 minutes to run from mile marker 2 to mile marker 4.

Now, add the two times together:

$7 \, \text{minutes} + 18 \, \text{minutes} = 25 \, \text{minutes}$

Therefore, it took Jimmy 25 minutes to run from mile marker 1 to mile marker 4.

Would you like more details or have any questions?

Here are 5 related questions:

1. What was Jimmy's average speed between mile marker 1 and mile marker 4?
2. How long would it take Jimmy to run the entire half-marathon at the same pace?
3. If Jimmy ran the second segment (from mile 2 to mile 4) faster, how much faster would his overall time be?
4. How can you calculate Jimmy's pace per mile for each segment?
5. If Jimmy's total time for the half-marathon was 2 hours, what would his average pace per mile be?

Tip: When adding times for multiple intervals, double-check each segment's duration to ensure accuracy.