At 8 a.m., Ryan started from City Y and travelled towards City Z and his speed remained constant throughout. At 9 a.m., Barbara started her journey from City Y towards City Z at an average speed of 90 km/h. Barbara overtook Ryan at 1 p.m. After overtaking, Barbara carried on her journey at the same average speed and reached at City Z at 5:40 p.m.
- Find Ryan'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 Barbara had travelled until Barbara overtook Ryan
= 4 x 90
= 360 km
From 8 a.m. to 1 p.m. = 5 h
Ryan's average speed
= 360 ÷ 5
= 72 km/h
(b)
From 9 a.m. to 5:40 p.m. = 8 h 40 min
1 h = 60 min
8 h 40 min = 8
40 60
h = 8
23 h
Distance between the two cities
= 8
23 x 90
=
263 x 90
= 780 km
Answer(s): (a) 72 km/h; (b) 780 km