Yoko left home at 11.25 a.m. and drove towards the countryside. 2 hours later, her father left their home and drove towards the same countryside at 92 km/h. When the father reached the countryside at 4.25 p.m., Yoko had another 4 km to travel. What was Yoko’s average speed? Express your answer in mixed number.
Time that the Yoko's father started driving = 1.25 p.m.
Duration that Yoko's father drove from 1.25 p.m. to 4.25 p.m. = 3 h

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

Distance that Yoko travelled by the time her father reached the city
= 276 - 4
= 272 km

Time that Yoko took to travel 272 km = 5 h

Yoko's average speed
= 272 ÷ 5
= 54²₅ km/h

Answer(s): 54²₅ km/h