At 7 a.m., Vincent started from City R and travelled towards City S and his speed remained constant throughout. At 8 a.m., Mary started her journey from City R towards City S at an average speed of 90 km/h. Mary overtook Vincent at 1 p.m. After overtaking, Mary carried on her journey at the same average speed and reached at City S at 4:50 p.m.

1. Find Vincent'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 Vincent
= 5 x 90
= 450 km

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

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

(b)
From 8 a.m. to 4:50 p.m. = 8 h 50 min

1 h = 60 min
8 h 50 min = 8 ⁵⁰ ₆₀
 h = 8 ⁵₆ h

Distance between the two cities
= 8 ⁵₆ x 90
= ⁵³₆ x 90
= 795 km

Answer(s): (a) 75 km/h; (b) 795 km