At 8 a.m., Mark started from City T and travelled towards City U and his speed remained constant throughout. At 10 a.m., Cindy started her journey from City T towards City U at an average speed of 80 km/h. Cindy overtook Mark at 1 p.m. After overtaking, Cindy carried on her journey at the same average speed and reached at City U at 2:15 p.m.

1. Find Mark's average speed in km/h.
2. What is the distance between the two cities?

(a)
From 10 a.m. to 1 p.m. = 3 h

Distance that Cindy had travelled until Cindy overtook Mark
= 3 x 80
= 240 km

From 8 a.m. to 1 p.m. = 5 h

Mark's average speed
= 240 ÷ 5
= 48 km/h

(b)
From 10 a.m. to 2:15 p.m. = 4 h 15 min

1 h = 60 min
4 h 15 min = 4 ¹⁵ ₆₀
 h = 4 ¹₄ h

Distance between the two cities
= 4 ¹₄ x 80
= ¹⁷₄ x 80
= 340 km

Answer(s): (a) 48 km/h; (b) 340 km