City N and City P are 525 km apart. At 6.56 p.m., Ahmad is travelling at a uniform speed left City N for City P while Riordan set off from City P to City N along the same road at a uniform speed, which was 5 km/h slower than that of Ahmad. The two met at 9.56 p.m.
- Find the speed of Ahmad.
- If Riordan 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 Ahmad and Riordan to travel from 6.56 p.m. to 9.56 p.m. = 3 h
Average speed of Ahmad and Riordan
= 525 ÷ 3
= 175 km/h
Ahmad's speed
= (175 + 5) ÷ 2
= 180 ÷ 2
= 90 km/h
(b)
Riordan's speed
= 90 - 5
= 85 km/h
Distance that Riordan travelled in 3 h
= 3 x 85
= 255 km
Remaining distance that Riordan needed to travel
= 525 - 255
= 270 km
Time that Riordan needed to reach his destination after the two met
= 270 ÷ 85
= 3
1585 = 3
317 h
Answer(s): (a) 90 km/h; (b) 3
317 h