City M and City N are 339 km apart. At 4.58 p.m., Seth is travelling at a uniform speed left City M for City N while Ryan set off from City N to City M along the same road at a uniform speed, which was 11 km/h slower than that of Seth. The two met at 7.58 p.m.
- Find the speed of Seth.
- If Ryan 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 Ryan to travel from 4.58 p.m. to 7.58 p.m. = 3 h
Average speed of Seth and Ryan
= 339 ÷ 3
= 113 km/h
Seth's speed
= (113 + 11) ÷ 2
= 124 ÷ 2
= 62 km/h
(b)
Ryan's speed
= 62 - 11
= 51 km/h
Distance that Ryan travelled in 3 h
= 3 x 51
= 153 km
Remaining distance that Ryan needed to travel
= 339 - 153
= 186 km
Time that Ryan needed to reach his destination after the two met
= 186 ÷ 51
= 3
3351 = 3
1117 h
Answer(s): (a) 62 km/h; (b) 3
1117 h