At 7 a.m., John started from City X and travelled towards City Y and his speed remained constant throughout. At 10 a.m., Gillian started her journey from City X towards City Y at an average speed of 68 km/h. Gillian overtook John at 1 p.m. After overtaking, Gillian carried on her journey at the same average speed and reached at City Y at 4:15 p.m.

1. Find John'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 Gillian had travelled until Gillian overtook John
= 3 x 68
= 204 km

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

John's average speed
= 204 ÷ 6
= 34 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 68
= ²⁵₄ x 68
= 425 km

Answer(s): (a) 34 km/h; (b) 425 km