Rachel left home at 11.15 a.m. and drove towards the campsite. 2 hours later, her father left their home and drove towards the same campsite at 92 km/h. When the father reached the campsite at 4.15 p.m., Rachel had another 3 km to travel. What was Rachel’s average speed? Express your answer in mixed number.
Time that the Rachel's father started driving = 1.15 p.m.
Duration that Rachel's father drove from 1.15 p.m. to 4.15 p.m. = 3 h

Distance that Rachel's father travelled
= 3 x 92
= 276 km

Distance that Rachel travelled by the time her father reached the city
= 276 - 3
= 273 km

Time that Rachel took to travel 273 km = 5 h

Rachel's average speed
= 273 ÷ 5
= 54³₅ km/h

Answer(s): 54³₅ km/h