At 9 a.m., Billy started from City W and travelled towards City X and his speed remained constant throughout. At 10 a.m., Kathy started her journey from City W towards City X at an average speed of 72 km/h. Kathy overtook Billy at 1 p.m. After overtaking, Kathy carried on her journey at the same average speed and reached at City X at 2:45 p.m.
- Find Billy's average speed in km/h.
- What is the distance between the two cities?
(a)
From 10 a.m. to 1 p.m. = 3 h
Distance that Kathy had travelled until Kathy overtook Billy
= 3 x 72
= 216 km
From 9 a.m. to 1 p.m. = 4 h
Billy's average speed
= 216 ÷ 4
= 54 km/h
(b)
From 10 a.m. to 2:45 p.m. = 4 h 45 min
1 h = 60 min
4 h 45 min = 4
45 60
h = 4
34 h
Distance between the two cities
= 4
34 x 72
=
194 x 72
= 342 km
Answer(s): (a) 54 km/h; (b) 342 km