Step 1: Speed ratio from race 1:
When Karan finishes 100 m, Arjun has run 90 m (Karan wins by 10 m). Same time, so Karan : Arjun speeds = 100 : 90 = 10 : 9.
Step 2: Second race:
Karan must now run 110 m, Arjun 100 m. Let speeds be 10v and 9v. Karan's time = 110/(10v) = 11/v. Arjun's time = 100/(9v) = 11.11/v.
Step 3: Compare:
Karan's time (11/v) is less than Arjun's (11.11/v), so Karan wins. When Karan finishes (time 11/v), Arjun has run 9v x 11/v = 99 m, i.e. he is 1 m short of the finish line.
Step 4: Conclusion:
Karan beats Arjun by 1 metre.
Final Answer:
The correct option is (1): Karan beats Arjun by 1 metre.