At 12 30, Warren left Town P for Town Q, driving at a speed of 81 km/h. At 14 30, Bobby also left Town P for Town Q driving at a certain speed. Both of them did not change their speed throughout the journey. At 17 30, both of them passed a mosque that was 243 km away from Town Q. How many minutes earlier did Bobby reach Town Q than Warren?

Distance that Warren travelled
= 5 x 81
= 405 km

Distance between Town P and Town Q
= 405 + 243
= 648 km

Since Bobby passed the mosque at the same time as Warren, it means that Bobby travelled 405 km in 3 hours.

Bobby's speed during the journey
= 405 ÷ 3
= 135 km/h

Duration that Bobby took to reach Town Q after passing the mosque
= 243 ÷ 135
= 1.8 h

Duration that Warren took to reach Town Q after passing the mosque
= 243 ÷ 81
= 3 h

Difference between the time they took to reach Town Q
= 3 - 1.8
= 1.2 h

1 h = 60 min
1.2 h = 1.2 x 60 = 72 min

Bobby reached Town Q 72 minutes earlier than Warren.

Answer(s): 72 min