At 8 a.m., Carl started from City T and travelled towards City U and his speed remained constant throughout. At 10 a.m., Emily started her journey from City T towards City U at an average speed of 90 km/h. Emily overtook Carl at 1 p.m. After overtaking, Emily carried on her journey at the same average speed and reached at City U at 6:30 p.m.
- Find Carl'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 Emily had travelled until Emily overtook Carl
= 3 x 90
= 270 km
From 8 a.m. to 1 p.m. = 5 h
Carl's average speed
= 270 ÷ 5
= 54 km/h
(b)
From 10 a.m. to 6:30 p.m. = 8 h 30 min
1 h = 60 min
8 h 30 min = 8
30 60
h = 8
12 h
Distance between the two cities
= 8
12 x 90
=
172 x 90
= 765 km
Answer(s): (a) 54 km/h; (b) 765 km