At 7 a.m., Tommy started from City Y and travelled towards City Z and his speed remained constant throughout. At 8 a.m., Mary started her journey from City Y towards City Z at an average speed of 90 km/h. Mary overtook Tommy at 1 p.m. After overtaking, Mary carried on her journey at the same average speed and reached at City Z at 5:50 p.m.

1. Find Tommy'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 Mary had travelled until Mary overtook Tommy
= 5 x 90
= 450 km

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

Tommy's average speed
= 450 ÷ 6
= 75 km/h

(b)
From 8 a.m. to 5:50 p.m. = 9 h 50 min

1 h = 60 min
9 h 50 min = 9 ⁵⁰ ₆₀
 h = 9 ⁵₆ h

Distance between the two cities
= 9 ⁵₆ x 90
= ⁵⁹₆ x 90
= 885 km

Answer(s): (a) 75 km/h; (b) 885 km