At 10 a.m., Joelle and Erika raced off together from the starting point of a track. Joelle ran at an average speed of 1 m/s. Erika ran at an average speed of 4 m/s. Upon reaching the end of the track, Erika rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 10.40 a.m., Joelle met Erika.

1. Find the total distance covered by the two runners when they met each other. Express your answer in km.
2. Find the length of the trail in km.

(a)
From 10 a.m. to 10.40 a.m. = 40 min

Duration that Joelle ran = 40 min
Duration that Erika ran = 40 -  4 = 36 min

1 min = 60 s

36 min = 36 x 60 = 2160 s
40 min = 40 x 60 = 2400 s

Distance that Joelle ran
= 1 x 2400
= 2400 m

Distance that Erika ran
= 4 x 2160
= 8640 m

Distance that Joelle and Erika ran
= 2400 + 8640
= 11040 m

1000 m = 1 km

11040 m = 11040 ÷ 1000 = 11.04 km

(b)
Length of the trail
= 11.04 ÷ 2
= 5.52 km

Answer(s): (a) 11.04 km; (b) 5.52 km