At 11 a.m., Raeann and Shiyun raced off together from the starting point of a route. Raeann ran at an average speed of 2 m/s. Shiyun ran at an average speed of 4 m/s. Upon reaching the end of the route, Shiyun rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 11.25 a.m., Raeann 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 11 a.m. to 11.25 a.m. = 25 min

Duration that Raeann ran = 25 min
Duration that Shiyun ran = 25 -  4 = 21 min

1 min = 60 s

21 min = 21 x 60 = 1260 s
25 min = 25 x 60 = 1500 s

Distance that Raeann ran
= 2 x 1500
= 3000 m

Distance that Shiyun ran
= 4 x 1260
= 5040 m

Distance that Raeann and Shiyun ran
= 3000 + 5040
= 8040 m

1000 m = 1 km

8040 m = 8040 ÷ 1000 = 8.04 km

(b)
Length of the trail
= 8.04 ÷ 2
= 4.02 km

Answer(s): (a) 8.04 km; (b) 4.02 km