At 7 a.m., Dylan started from City X and travelled towards City Y and his speed remained constant throughout. At 8 a.m., Gwen started her journey from City X towards City Y at an average speed of 78 km/h. Gwen overtook Dylan at 1 p.m. After overtaking, Gwen carried on her journey at the same average speed and reached at City Y at 6:40 p.m.
- Find Dylan's average speed in km/h.
- What is the distance between the two cities?
(a)
From 8 a.m. to 1 p.m. = 5 h
Distance that Gwen had travelled until Gwen overtook Dylan
= 5 x 78
= 390 km
From 7 a.m. to 1 p.m. = 6 h
Dylan's average speed
= 390 ÷ 6
= 65 km/h
(b)
From 8 a.m. to 6:40 p.m. = 10 h 40 min
1 h = 60 min
10 h 40 min = 10
40 60
h = 10
23 h
Distance between the two cities
= 10
23 x 78
=
323 x 78
= 832 km
Answer(s): (a) 65 km/h; (b) 832 km