Hazel left home at 10.55 a.m. and drove towards the town. 3 hours later, her younger brother left their home and drove towards the same town at 100 km/h. When the younger brother reached the town at 6.55 p.m., Hazel had another 4 km to travel. What was Hazel’s average speed? Express your answer in mixed number.
Time that the Hazel's younger brother started driving = 1.55 p.m.
Duration that Hazel's younger brother drove from 1.55 p.m. to 6.55 p.m. = 5 h

Distance that Hazel's younger brother travelled
= 5 x 100
= 500 km

Distance that Hazel travelled by the time her younger brother reached the city
= 500 - 4
= 496 km

Time that Hazel took to travel 496 km = 8 h

Hazel's average speed
= 496 ÷ 8
= 62 km/h

Answer(s): 62 km/h