At 8 a.m., Albert started from City D and travelled towards City E and his speed remained constant throughout. At 9 a.m., Xuan started her journey from City D towards City E at an average speed of 84 km/h. Xuan overtook Albert at 2 p.m. After overtaking, Xuan carried on her journey at the same average speed and reached at City E at 1:25 p.m.

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

(a)
From 9 a.m. to 2 p.m. = 5 h

Distance that Xuan had travelled until Xuan overtook Albert
= 5 x 84
= 420 km

From 8 a.m. to 2 p.m. = 6 h

Albert's average speed
= 420 ÷ 6
= 70 km/h

(b)
From 9 a.m. to 1:25 p.m. = 4 h 25 min

1 h = 60 min
4 h 25 min = 4 ²⁵ ₆₀
 h = 4 ⁵₁₂ h

Distance between the two cities
= 4 ⁵₁₂ x 84
= ⁵³₁₂ x 84
= 371 km

Answer(s): (a) 70 km/h; (b) 371 km