At 10 a.m., Xuan and Shiyun raced off together from the starting point of a path. Xuan ran at an average speed of 2 m/s. Shiyun ran at an average speed of 3 m/s. Upon reaching the end of the path, Shiyun rested for 5 minutes. She then immediately ran back along the same route at 3 m/s. At 10.30 a.m., Xuan met Shiyun.

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 10.30 a.m. = 30 min

Duration that Xuan ran = 30 min
Duration that Shiyun ran = 30 -  5 = 25 min

1 min = 60 s

25 min = 25 x 60 = 1500 s
30 min = 30 x 60 = 1800 s

Distance that Xuan ran
= 2 x 1800
= 3600 m

Distance that Shiyun ran
= 3 x 1500
= 4500 m

Distance that Xuan and Shiyun ran
= 3600 + 4500
= 8100 m

1000 m = 1 km

8100 m = 8100 ÷ 1000 = 8.1 km

(b)
Length of the trail
= 8.1 ÷ 2
= 4.05 km

Answer(s): (a) 8.1 km; (b) 4.05 km