City N and City P are 348 km apart. At 6.11 p.m., David is travelling at a uniform speed left City N for City P while Harry set off from City P to City N along the same road at a uniform speed, which was 8 km/h slower than that of David. The two met at 9.11 p.m.
- Find the speed of David.
- If Harry 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 David and Harry to travel from 6.11 p.m. to 9.11 p.m. = 3 h
Average speed of David and Harry
= 348 ÷ 3
= 116 km/h
David's speed
= (116 + 8) ÷ 2
= 124 ÷ 2
= 62 km/h
(b)
Harry's speed
= 62 - 8
= 54 km/h
Distance that Harry travelled in 3 h
= 3 x 54
= 162 km
Remaining distance that Harry needed to travel
= 348 - 162
= 186 km
Time that Harry needed to reach his destination after the two met
= 186 ÷ 54
= 3
2454 = 3
49 h
Answer(s): (a) 62 km/h; (b) 3
49 h