City W and City X is 490 km apart. David left City W for City X at 11.00 a.m. travelling at an average speed of 70 km/h. Julian left City W later than David and caught up with him at 1.00 p.m. Julian was travelling at a speed of 80 km/h.

1. At what time did Julian leave City W?
2. How much later did David arrive in City X than Julian? Express your answer in h as a fraction or mixed number.

(a)
From 11.00 a.m. to 1.00 p.m. = 2 h

Distance that David covered when Julian caught up with David
= 2 x 70
= 140 km

Time that Julian took to travel 140 km
= 140 ÷ 80
= 1³₄ h

1 h = 60 min
³₄ h = ³₄ x 60 = 45 min
1³₄ h = 1 h 45 min

Time that Julian left City W:
1 h 45 min before 1.00 p.m. = 11.15 a.m.

(b)
Remaining distance that they had to cover to reach City X
= 490 - 140
= 350 km

Duration that Julian had to travel before reaching City X
= 350 ÷ 80
= 4³₈ h

Duration that David had to travel before reaching City X
= 350 ÷ 70
= 5 h

Duration that David took to arrive later than Julian in City X
= 5 - 4³₈
= ⁵₈ h

Answer(s): (a) 11.15 a.m.; (b) ⁵₈ h