At 10 a.m., Hazel and Yen raced off together from the starting point of a course. Hazel ran at an average speed of 1 m/s. Yen ran at an average speed of 3 m/s. Upon reaching the end of the course, Yen rested for 3 minutes. She then immediately ran back along the same route at 3 m/s. At 10.40 a.m., Hazel met Yen.

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 10 a.m. to 10.40 a.m. = 40 min

Duration that Hazel ran = 40 min
Duration that Yen 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 Hazel ran
= 1 x 2400
= 2400 m

Distance that Yen ran
= 3 x 2220
= 6660 m

Distance that Hazel and Yen ran
= 2400 + 6660
= 9060 m

1000 m = 1 km

9060 m = 9060 ÷ 1000 = 9.06 km

(b)
Length of the trail
= 9.06 ÷ 2
= 4.53 km

Answer(s): (a) 9.06 km; (b) 4.53 km