At 7 a.m., David started from City N and travelled towards City P and his speed remained constant throughout. At 8 a.m., Tammy started her journey from City N towards City P at an average speed of 66 km/h. Tammy overtook David at 1 p.m. After overtaking, Tammy carried on her journey at the same average speed and reached at City P at 3:40 p.m.
- Find David's average speed in km/h.
- What is the distance between the two cities?
(a)
From 8 a.m. to 1 p.m. = 5 h
Distance that Tammy had travelled until Tammy overtook David
= 5 x 66
= 330 km
From 7 a.m. to 1 p.m. = 6 h
David's average speed
= 330 ÷ 6
= 55 km/h
(b)
From 8 a.m. to 3:40 p.m. = 7 h 40 min
1 h = 60 min
7 h 40 min = 7
40 60
h = 7
23 h
Distance between the two cities
= 7
23 x 66
=
233 x 66
= 506 km
Answer(s): (a) 55 km/h; (b) 506 km