Answer:
faster than 100 kph
Explanation:
Time taken to complete the first lap is
[tex]\dfrac{15\ \text{km}}{15\ \text{kph}}=1\ \text{hour}[/tex]
If the person's average speed is to be 30 kph then the complete race would be over in [tex]\dfrac{30}{30}=1\ \text{hour}[/tex]
But 1 hour has passed in the first lap already so, the next 15 km must be covered in 0 time.
So, the speed of the bike must be more than 100 kph.