City D and City E are 486 km apart. At 5.35 p.m., Ahmad is travelling at a uniform speed left City D for City E while Harry set off from City E to City D along the same road at a uniform speed, which was 6 km/h slower than that of Ahmad. The two met at 8.35 p.m.
- Find the speed of Ahmad.
- 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 Ahmad and Harry to travel from 5.35 p.m. to 8.35 p.m. = 3 h
Average speed of Ahmad and Harry
= 486 ÷ 3
= 162 km/h
Ahmad's speed
= (162 + 6) ÷ 2
= 168 ÷ 2
= 84 km/h
(b)
Harry's speed
= 84 - 6
= 78 km/h
Distance that Harry travelled in 3 h
= 3 x 78
= 234 km
Remaining distance that Harry needed to travel
= 486 - 234
= 252 km
Time that Harry needed to reach his destination after the two met
= 252 ÷ 78
= 3
1878 = 3
313 h
Answer(s): (a) 84 km/h; (b) 3
313 h