At 9 a.m., Sabrina and Shannon raced off together from the starting point of a route. Sabrina ran at an average speed of 3 m/s. Shannon ran at an average speed of 4 m/s. Upon reaching the end of the route, Shannon rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 9.35 a.m., Sabrina met Shannon.

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 9 a.m. to 9.35 a.m. = 35 min

Duration that Sabrina ran = 35 min
Duration that Shannon ran = 35 -  4 = 31 min

1 min = 60 s

31 min = 31 x 60 = 1860 s
35 min = 35 x 60 = 2100 s

Distance that Sabrina ran
= 3 x 2100
= 6300 m

Distance that Shannon ran
= 4 x 1860
= 7440 m

Distance that Sabrina and Shannon ran
= 6300 + 7440
= 13740 m

1000 m = 1 km

13740 m = 13740 ÷ 1000 = 13.74 km

(b)
Length of the trail
= 13.74 ÷ 2
= 6.87 km

Answer(s): (a) 13.74 km; (b) 6.87 km