City M and City N are 572 km apart. At 2.58 p.m., Seth is travelling at a uniform speed left City M for City N while Oscar set off from City N to City M along the same road at a uniform speed, which was 7 km/h slower than that of Seth. The two met at 6.58 p.m.
- Find the speed of Seth.
- If Oscar 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 Seth and Oscar to travel from 2.58 p.m. to 6.58 p.m. = 4 h
Average speed of Seth and Oscar
= 572 ÷ 4
= 143 km/h
Seth's speed
= (143 + 7) ÷ 2
= 150 ÷ 2
= 75 km/h
(b)
Oscar's speed
= 75 - 7
= 68 km/h
Distance that Oscar travelled in 4 h
= 4 x 68
= 272 km
Remaining distance that Oscar needed to travel
= 572 - 272
= 300 km
Time that Oscar needed to reach his destination after the two met
= 300 ÷ 68
= 4
2868 = 4
717 h
Answer(s): (a) 75 km/h; (b) 4
717 h