Marion left home at 10.15 a.m. and drove towards the countryside. 3 hours later, her uncle left their home and drove towards the same countryside at 88 km/h. When the uncle reached the countryside at 6.15 p.m., Marion had another 4 km to travel. What was Marion’s average speed? Express your answer in mixed number.
Time that the Marion's uncle started driving = 1.15 p.m.
Duration that Marion's uncle drove from 1.15 p.m. to 6.15 p.m. = 5 h

Distance that Marion's uncle travelled
= 5 x 88
= 440 km

Distance that Marion travelled by the time her uncle reached the city
= 440 - 4
= 436 km

Time that Marion took to travel 436 km = 8 h

Marion's average speed
= 436 ÷ 8
= 54¹₂ km/h

Answer(s): 54¹₂ km/h