City D and City E are 384 km apart. At 4.44 p.m., Japheth is travelling at a uniform speed left City D for City E while Elijah set off from City E to City D along the same road at a uniform speed, which was 8 km/h slower than that of Japheth. The two met at 7.44 p.m.
- Find the speed of Japheth.
- If Elijah 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 Japheth and Elijah to travel from 4.44 p.m. to 7.44 p.m. = 3 h
Average speed of Japheth and Elijah
= 384 ÷ 3
= 128 km/h
Japheth's speed
= (128 + 8) ÷ 2
= 136 ÷ 2
= 68 km/h
(b)
Elijah's speed
= 68 - 8
= 60 km/h
Distance that Elijah travelled in 3 h
= 3 x 60
= 180 km
Remaining distance that Elijah needed to travel
= 384 - 180
= 204 km
Time that Elijah needed to reach his destination after the two met
= 204 ÷ 60
= 3
2460 = 3
25 h
Answer(s): (a) 68 km/h; (b) 3
25 h