City L and City M are 342 km apart. At 4.15 p.m., Dylan is travelling at a uniform speed left City L for City M while Bobby set off from City M to City L along the same road at a uniform speed, which was 12 km/h slower than that of Dylan. The two met at 7.15 p.m.
- Find the speed of Dylan.
- If Bobby 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 Dylan and Bobby to travel from 4.15 p.m. to 7.15 p.m. = 3 h
Average speed of Dylan and Bobby
= 342 ÷ 3
= 114 km/h
Dylan's speed
= (114 + 12) ÷ 2
= 126 ÷ 2
= 63 km/h
(b)
Bobby's speed
= 63 - 12
= 51 km/h
Distance that Bobby travelled in 3 h
= 3 x 51
= 153 km
Remaining distance that Bobby needed to travel
= 342 - 153
= 189 km
Time that Bobby needed to reach his destination after the two met
= 189 ÷ 51
= 3
3651 = 3
1217 h
Answer(s): (a) 63 km/h; (b) 3
1217 h