City F and City G is 480 km apart. Peter left City F for City G at 9.00 a.m. travelling at an average speed of 60 km/h. Lee left City F later than Peter and caught up with him at 1.00 p.m. Lee was travelling at a speed of 90 km/h.

1. At what time did Lee leave City F?
2. How much later did Peter arrive in City G than Lee? Express your answer in h as a fraction or mixed number.

(a)
From 9.00 a.m. to 1.00 p.m. = 4 h

Distance that Peter covered when Lee caught up with Peter
= 4 x 60
= 240 km

Time that Lee took to travel 240 km
= 240 ÷ 90
= 2²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
2²₃ h = 2 h 40 min

Time that Lee left City F:
2 h 40 min before 1.00 p.m. = 10.20 a.m.

(b)
Remaining distance that they had to cover to reach City G
= 480 - 240
= 240 km

Duration that Lee had to travel before reaching City G
= 240 ÷ 90
= 2²₃ h

Duration that Peter had to travel before reaching City G
= 240 ÷ 60
= 4 h

Duration that Peter took to arrive later than Lee in City G
= 4 - 2²₃
= 1¹₃ h

Answer(s): (a) 10.20 a.m.; (b) 1¹₃ h