At 8 a.m., Eric started from City L and travelled towards City M and his speed remained constant throughout. At 10 a.m., Sarah started her journey from City L towards City M at an average speed of 72 km/h. Sarah overtook Eric at 2 p.m. After overtaking, Sarah carried on her journey at the same average speed and reached at City M at 6:45 p.m.

1. Find Eric'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 Sarah had travelled until Sarah overtook Eric
= 4 x 72
= 288 km

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

Eric's average speed
= 288 ÷ 6
= 48 km/h

(b)
From 10 a.m. to 6:45 p.m. = 8 h 45 min

1 h = 60 min
8 h 45 min = 8 ⁴⁵ ₆₀
 h = 8 ³₄ h

Distance between the two cities
= 8 ³₄ x 72
= ³⁵₄ x 72
= 630 km

Answer(s): (a) 48 km/h; (b) 630 km