At 11 a.m., Xuan and Sarah raced off together from the starting point of a path. Xuan ran at an average speed of 3 m/s. Sarah ran at an average speed of 4 m/s. Upon reaching the end of the path, Sarah rested for 5 minutes. She then immediately ran back along the same route at 4 m/s. At 11.30 a.m., Xuan met Sarah.

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 11 a.m. to 11.30 a.m. = 30 min

Duration that Xuan ran = 30 min
Duration that Sarah 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
= 3 x 1800
= 5400 m

Distance that Sarah ran
= 4 x 1500
= 6000 m

Distance that Xuan and Sarah ran
= 5400 + 6000
= 11400 m

1000 m = 1 km

11400 m = 11400 ÷ 1000 = 11.4 km

(b)
Length of the trail
= 11.4 ÷ 2
= 5.7 km

Answer(s): (a) 11.4 km; (b) 5.7 km