At 7 a.m., Wendy and Olivia raced off together from the starting point of a track. Wendy ran at an average speed of 1 m/s. Olivia ran at an average speed of 2 m/s. Upon reaching the end of the track, Olivia rested for 4 minutes. She then immediately ran back along the same route at 2 m/s. At 7.40 a.m., Wendy met Olivia.

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 Wendy ran = 40 min
Duration that Olivia 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 Wendy ran
= 1 x 2400
= 2400 m

Distance that Olivia ran
= 2 x 2160
= 4320 m

Distance that Wendy and Olivia ran
= 2400 + 4320
= 6720 m

1000 m = 1 km

6720 m = 6720 ÷ 1000 = 6.72 km

(b)
Length of the trail
= 6.72 ÷ 2
= 3.36 km

Answer(s): (a) 6.72 km; (b) 3.36 km