Cindy left home at 10.50 a.m. and drove towards the province. 3 hours later, her younger sister left their home and drove towards the same province at 83 km/h. When the younger sister reached the province at 6.50 p.m., Cindy had another 5 km to travel. What was Cindy’s average speed? Express your answer in mixed number.
Time that the Cindy's younger sister started driving = 1.50 p.m.
Duration that Cindy's younger sister drove from 1.50 p.m. to 6.50 p.m. = 5 h

Distance that Cindy's younger sister travelled
= 5 x 83
= 415 km

Distance that Cindy travelled by the time her younger sister reached the city
= 415 - 5
= 410 km

Time that Cindy took to travel 410 km = 8 h

Cindy's average speed
= 410 ÷ 8
= 51¹₄ km/h

Answer(s): 51¹₄ km/h