At 9 a.m., Jack started from City H and travelled towards City J and his speed remained constant throughout. At 10 a.m., Lucy started her journey from City H towards City J at an average speed of 84 km/h. Lucy overtook Jack at 3 p.m. After overtaking, Lucy carried on her journey at the same average speed and reached at City J at 6:50 p.m.
- Find Jack's average speed in km/h.
- What is the distance between the two cities?
(a)
From 10 a.m. to 3 p.m. = 5 h
Distance that Lucy had travelled until Lucy overtook Jack
= 5 x 84
= 420 km
From 9 a.m. to 3 p.m. = 6 h
Jack's average speed
= 420 ÷ 6
= 70 km/h
(b)
From 10 a.m. to 6:50 p.m. = 8 h 50 min
1 h = 60 min
8 h 50 min = 8
50 60
h = 8
56 h
Distance between the two cities
= 8
56 x 84
=
536 x 84
= 742 km
Answer(s): (a) 70 km/h; (b) 742 km