City S and City T are 336 km apart. At 2.36 p.m., Sam is travelling at a uniform speed left City S for City T while Flynn set off from City T to City S along the same road at a uniform speed, which was 12 km/h slower than that of Sam. The two met at 4.36 p.m.
- Find the speed of Sam.
- If Flynn 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 Sam and Flynn to travel from 2.36 p.m. to 4.36 p.m. = 2 h
Average speed of Sam and Flynn
= 336 ÷ 2
= 168 km/h
Sam's speed
= (168 + 12) ÷ 2
= 180 ÷ 2
= 90 km/h
(b)
Flynn's speed
= 90 - 12
= 78 km/h
Distance that Flynn travelled in 2 h
= 2 x 78
= 156 km
Remaining distance that Flynn needed to travel
= 336 - 156
= 180 km
Time that Flynn needed to reach his destination after the two met
= 180 ÷ 78
= 2
2478 = 2
413 h
Answer(s): (a) 90 km/h; (b) 2
413 h