Winnie left home at 11.40 a.m. and drove towards the campsite. 2 hours later, her mother left their home and drove towards the same campsite at 88 km/h. When the mother reached the campsite at 5.40 p.m., Winnie had another 4 km to travel. What was Winnie’s average speed? Express your answer in mixed number.
Time that the Winnie's mother started driving = 1.40 p.m.
Duration that Winnie's mother drove from 1.40 p.m. to 5.40 p.m. = 4 h

Distance that Winnie's mother travelled
= 4 x 88
= 352 km

Distance that Winnie travelled by the time her mother reached the city
= 352 - 4
= 348 km

Time that Winnie took to travel 348 km = 6 h

Winnie's average speed
= 348 ÷ 6
= 58 km/h

Answer(s): 58 km/h