Question 7
In a car race, a driver covered three sections: one of $240~\mathrm{km}$, one of $300~\mathrm{km}$ and one of $400~\mathrm{km}$. The pilot knows that the average speeds in these sections were $40~\mathrm{km}/\mathrm{h}$, $75~\mathrm{km}/\mathrm{h}$ and $80~\mathrm{km}/\mathrm{h}$, but he does not remember which of these speeds corresponds to each of these sections. We can guarantee that the total time in hours spent by the pilot to cover the three sections was:
A) less than or equal to 13 hours
B) greater than or equal to 13 hours and less than or equal to 16 hours
C) greater than or equal to 16 hours and less than or equal to 17 hours
D) greater than or equal to 15 hours and less than or equal to 18 hours
E) greater than or equal to 18 hours
A) less than or equal to 13 hours
B) greater than or equal to 13 hours and less than or equal to 16 hours
C) greater than or equal to 16 hours and less than or equal to 17 hours
D) greater than or equal to 15 hours and less than or equal to 18 hours
E) greater than or equal to 18 hours