City N and City P are 378 km apart. At 2.12 p.m., Ian is travelling at a uniform speed left City N for City P while Mark set off from City P to City N along the same road at a uniform speed, which was 6 km/h slower than that of Ian. The two met at 5.12 p.m.

1. Find the speed of Ian.
2. If Mark 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 Mark to travel from 2.12 p.m. to 5.12 p.m. = 3 h

Average speed of Ian and Mark
= 378 ÷ 3
= 126 km/h

Ian's speed
= (126 + 6) ÷ 2
= 132 ÷ 2 
= 66 km/h

(b)
Mark's speed
= 66 - 6
= 60 km/h

Distance that Mark travelled in 3 h
= 3 x 60
= 180 km

Remaining distance that Mark needed to travel
= 378 - 180
= 198 km

Time that Mark needed to reach his destination after the two met
= 198 ÷ 60
= 3¹⁸₆₀
= 3³₁₀ h

Answer(s): (a) 66 km/h; (b) 3³₁₀ h