At 7 a.m., Daniel started from City Z and travelled towards City A and his speed remained constant throughout. At 10 a.m., Yen started her journey from City Z towards City A at an average speed of 72 km/h. Yen overtook Daniel at 1 p.m. After overtaking, Yen carried on her journey at the same average speed and reached at City A at 4:15 p.m.

1. Find Daniel'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 Yen had travelled until Yen overtook Daniel
= 3 x 72
= 216 km

From 7 a.m. to 1 p.m. = 6 h

Daniel's average speed
= 216 ÷ 6
= 36 km/h

(b)
From 10 a.m. to 4:15 p.m. = 6 h 15 min

1 h = 60 min
6 h 15 min = 6 ¹⁵ ₆₀
 h = 6 ¹₄ h

Distance between the two cities
= 6 ¹₄ x 72
= ²⁵₄ x 72
= 450 km

Answer(s): (a) 36 km/h; (b) 450 km