Xylia left home at 11.50 a.m. and drove towards the campsite. 3 hours later, her grandfather left their home and drove towards the same campsite at 98 km/h. When the grandfather reached the campsite at 7.50 p.m., Xylia had another 4 km to travel. What was Xylia’s average speed? Express your answer in mixed number.
Time that the Xylia's grandfather started driving = 2.50 p.m.
Duration that Xylia's grandfather drove from 2.50 p.m. to 7.50 p.m. = 5 h

Distance that Xylia's grandfather travelled
= 5 x 98
= 490 km

Distance that Xylia travelled by the time her grandfather reached the city
= 490 - 4
= 486 km

Time that Xylia took to travel 486 km = 8 h

Xylia's average speed
= 486 ÷ 8
= 60³₄ km/h

Answer(s): 60³₄ km/h