Winnie left home at 10.50 a.m. and drove towards the campsite. 3 hours later, her older brother left their home and drove towards the same campsite at 92 km/h. When the older brother reached the campsite at 6.50 p.m., Winnie had another 2 km to travel. What was Winnie’s average speed? Express your answer in mixed number.
Time that the Winnie's older brother started driving = 1.50 p.m.
Duration that Winnie's older brother drove from 1.50 p.m. to 6.50 p.m. = 5 h

Distance that Winnie's older brother travelled
= 5 x 92
= 460 km

Distance that Winnie travelled by the time her older brother reached the city
= 460 - 2
= 458 km

Time that Winnie took to travel 458 km = 8 h

Winnie's average speed
= 458 ÷ 8
= 57¹₄ km/h

Answer(s): 57¹₄ km/h