At 7 a.m., Carl started from City G and travelled towards City H and his speed remained constant throughout. At 8 a.m., Hazel started her journey from City G towards City H at an average speed of 78 km/h. Hazel overtook Carl at 1 p.m. After overtaking, Hazel carried on her journey at the same average speed and reached at City H at 3:20 p.m.

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

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

Distance that Hazel had travelled until Hazel overtook Carl
= 5 x 78
= 390 km

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

Carl's average speed
= 390 ÷ 6
= 65 km/h

(b)
From 8 a.m. to 3:20 p.m. = 7 h 20 min

1 h = 60 min
7 h 20 min = 7 ²⁰ ₆₀
 h = 7 ¹₃ h

Distance between the two cities
= 7 ¹₃ x 78
= ²²₃ x 78
= 572 km

Answer(s): (a) 65 km/h; (b) 572 km