At 7 a.m., Ian started from City S and travelled towards City T and his speed remained constant throughout. At 9 a.m., Erika started her journey from City S towards City T at an average speed of 72 km/h. Erika overtook Ian at 1 p.m. After overtaking, Erika carried on her journey at the same average speed and reached at City T at 5:20 p.m.
- Find Ian'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 Erika had travelled until Erika overtook Ian
= 4 x 72
= 288 km
From 7 a.m. to 1 p.m. = 6 h
Ian's average speed
= 288 ÷ 6
= 48 km/h
(b)
From 9 a.m. to 5:20 p.m. = 8 h 20 min
1 h = 60 min
8 h 20 min = 8
20 60
h = 8
13 h
Distance between the two cities
= 8
13 x 72
=
253 x 72
= 600 km
Answer(s): (a) 48 km/h; (b) 600 km