At 8 a.m., Xuan and Emily raced off together from the starting point of a course. Xuan ran at an average speed of 2 m/s. Emily ran at an average speed of 4 m/s. Upon reaching the end of the course, Emily rested for 6 minutes. She then immediately ran back along the same route at 4 m/s. At 8.45 a.m., Xuan met Emily.

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 8 a.m. to 8.45 a.m. = 45 min

Duration that Xuan ran = 45 min
Duration that Emily ran = 45 -  6 = 39 min

1 min = 60 s

39 min = 39 x 60 = 2340 s
45 min = 45 x 60 = 2700 s

Distance that Xuan ran
= 2 x 2700
= 5400 m

Distance that Emily ran
= 4 x 2340
= 9360 m

Distance that Xuan and Emily ran
= 5400 + 9360
= 14760 m

1000 m = 1 km

14760 m = 14760 ÷ 1000 = 14.76 km

(b)
Length of the trail
= 14.76 ÷ 2
= 7.38 km

Answer(s): (a) 14.76 km; (b) 7.38 km