Penelope left home at 11.30 a.m. and drove towards the campsite. 2 hours later, her grandfather left their home and drove towards the same campsite at 92 km/h. When the grandfather reached the campsite at 4.30 p.m., Penelope had another 6 km to travel. What was Penelope’s average speed? Express your answer in mixed number.
Time that the Penelope's grandfather started driving = 1.30 p.m.
Duration that Penelope's grandfather drove from 1.30 p.m. to 4.30 p.m. = 3 h

Distance that Penelope's grandfather travelled
= 3 x 92
= 276 km

Distance that Penelope travelled by the time her grandfather reached the city
= 276 - 6
= 270 km

Time that Penelope took to travel 270 km = 5 h

Penelope's average speed
= 270 ÷ 5
= 54 km/h

Answer(s): 54 km/h