Natalie left home at 10.30 a.m. and drove towards the suburb. 3 hours later, her father left their home and drove towards the same suburb at 99 km/h. When the father reached the suburb at 6.30 p.m., Natalie had another 5 km to travel. What was Natalie’s average speed? Express your answer in mixed number.
Time that the Natalie's father started driving = 1.30 p.m.
Duration that Natalie's father drove from 1.30 p.m. to 6.30 p.m. = 5 h

Distance that Natalie's father travelled
= 5 x 99
= 495 km

Distance that Natalie travelled by the time her father reached the city
= 495 - 5
= 490 km

Time that Natalie took to travel 490 km = 8 h

Natalie's average speed
= 490 ÷ 8
= 61¹₄ km/h

Answer(s): 61¹₄ km/h