At 7 a.m., Gem and Elyse raced off together from the starting point of a track. Gem ran at an average speed of 2 m/s. Elyse ran at an average speed of 4 m/s. Upon reaching the end of the track, Elyse rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 7.40 a.m., Gem met Elyse.

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 7 a.m. to 7.40 a.m. = 40 min

Duration that Gem ran = 40 min
Duration that Elyse ran = 40 -  3 = 37 min

1 min = 60 s

37 min = 37 x 60 = 2220 s
40 min = 40 x 60 = 2400 s

Distance that Gem ran
= 2 x 2400
= 4800 m

Distance that Elyse ran
= 4 x 2220
= 8880 m

Distance that Gem and Elyse ran
= 4800 + 8880
= 13680 m

1000 m = 1 km

13680 m = 13680 ÷ 1000 = 13.68 km

(b)
Length of the trail
= 13.68 ÷ 2
= 6.84 km

Answer(s): (a) 13.68 km; (b) 6.84 km