City R and City S are 570 km apart. At 1.21 p.m., Ian is travelling at a uniform speed left City R for City S while Caden set off from City S to City R along the same road at a uniform speed, which was 10 km/h slower than that of Ian. The two met at 4.21 p.m.

1. Find the speed of Ian.
2. If Caden continued to travel at the same speed, how long would it take for him to reach his destination after the two met? Express your answer in mixed number.

(a)
Time taken for Ian and Caden to travel from 1.21 p.m. to 4.21 p.m. = 3 h

Average speed of Ian and Caden
= 570 ÷ 3
= 190 km/h

Ian's speed
= (190 + 10) ÷ 2
= 200 ÷ 2 
= 100 km/h

(b)
Caden's speed
= 100 - 10
= 90 km/h

Distance that Caden travelled in 3 h
= 3 x 90
= 270 km

Remaining distance that Caden needed to travel
= 570 - 270
= 300 km

Time that Caden needed to reach his destination after the two met
= 300 ÷ 90
= 3³⁰₉₀
= 3¹₃ h

Answer(s): (a) 100 km/h; (b) 3¹₃ h