At 9 a.m., Rachel and Linda raced off together from the starting point of a track. Rachel ran at an average speed of 2 m/s. Linda ran at an average speed of 4 m/s. Upon reaching the end of the track, Linda rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 9.40 a.m., Rachel met Linda.

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 9 a.m. to 9.40 a.m. = 40 min

Duration that Rachel ran = 40 min
Duration that Linda 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 Rachel ran
= 2 x 2400
= 4800 m

Distance that Linda ran
= 4 x 2160
= 8640 m

Distance that Rachel and Linda ran
= 4800 + 8640
= 13440 m

1000 m = 1 km

13440 m = 13440 ÷ 1000 = 13.44 km

(b)
Length of the trail
= 13.44 ÷ 2
= 6.72 km

Answer(s): (a) 13.44 km; (b) 6.72 km