At 11 a.m., Shannon and Sarah raced off together from the starting point of a course. Shannon 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 course, Sarah rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 11.40 a.m., Shannon 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 11.40 a.m. = 40 min

Duration that Shannon ran = 40 min
Duration that Sarah ran = 40 -  3 = 37 min

1 min = 60 s

37 min = 37 x 60 = 2220 s
40 min = 40 x 60 = 2400 s

Distance that Shannon ran
= 3 x 2400
= 7200 m

Distance that Sarah ran
= 4 x 2220
= 8880 m

Distance that Shannon and Sarah ran
= 7200 + 8880
= 16080 m

1000 m = 1 km

16080 m = 16080 ÷ 1000 = 16.08 km

(b)
Length of the trail
= 16.08 ÷ 2
= 8.04 km

Answer(s): (a) 16.08 km; (b) 8.04 km