City Y and City Z are 548 km apart. At 3.40 p.m., Fred is travelling at a uniform speed left City Y for City Z while Billy set off from City Z to City Y along the same road at a uniform speed, which was 9 km/h slower than that of Fred. The two met at 7.40 p.m.
- Find the speed of Fred.
- If Billy 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 Fred and Billy to travel from 3.40 p.m. to 7.40 p.m. = 4 h
Average speed of Fred and Billy
= 548 ÷ 4
= 137 km/h
Fred's speed
= (137 + 9) ÷ 2
= 146 ÷ 2
= 73 km/h
(b)
Billy's speed
= 73 - 9
= 64 km/h
Distance that Billy travelled in 4 h
= 4 x 64
= 256 km
Remaining distance that Billy needed to travel
= 548 - 256
= 292 km
Time that Billy needed to reach his destination after the two met
= 292 ÷ 64
= 4
3664 = 4
916 h
Answer(s): (a) 73 km/h; (b) 4
916 h