At 7 a.m., Ethan started from City X and travelled towards City Y and his speed remained constant throughout. At 9 a.m., Opal started her journey from City X towards City Y at an average speed of 72 km/h. Opal overtook Ethan at 1 p.m. After overtaking, Opal carried on her journey at the same average speed and reached at City Y at 1:20 p.m.
- Find Ethan's average speed in km/h.
- What is the distance between the two cities?
(a)
From 9 a.m. to 1 p.m. = 4 h
Distance that Opal had travelled until Opal overtook Ethan
= 4 x 72
= 288 km
From 7 a.m. to 1 p.m. = 6 h
Ethan's average speed
= 288 ÷ 6
= 48 km/h
(b)
From 9 a.m. to 1:20 p.m. = 4 h 20 min
1 h = 60 min
4 h 20 min = 4
20 60
h = 4
13 h
Distance between the two cities
= 4
13 x 72
=
133 x 72
= 312 km
Answer(s): (a) 48 km/h; (b) 312 km