At 8 a.m., Jack started from City J and travelled towards City K and his speed remained constant throughout. At 10 a.m., Mary started her journey from City J towards City K at an average speed of 75 km/h. Mary overtook Jack at 2 p.m. After overtaking, Mary carried on her journey at the same average speed and reached at City K at 5:20 p.m.

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

(a)
From 10 a.m. to 2 p.m. = 4 h

Distance that Mary had travelled until Mary overtook Jack
= 4 x 75
= 300 km

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

Jack's average speed
= 300 ÷ 6
= 50 km/h

(b)
From 10 a.m. to 5:20 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 75
= ²²₃ x 75
= 550 km

Answer(s): (a) 50 km/h; (b) 550 km