At 9 a.m., Barbara and Min raced off together from the starting point of a course. Barbara ran at an average speed of 2 m/s. Min ran at an average speed of 4 m/s. Upon reaching the end of the course, Min rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 9.50 a.m., Barbara met Min.

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 9.50 a.m. = 50 min

Duration that Barbara ran = 50 min
Duration that Min ran = 50 -  4 = 46 min

1 min = 60 s

46 min = 46 x 60 = 2760 s
50 min = 50 x 60 = 3000 s

Distance that Barbara ran
= 2 x 3000
= 6000 m

Distance that Min ran
= 4 x 2760
= 11040 m

Distance that Barbara and Min ran
= 6000 + 11040
= 17040 m

1000 m = 1 km

17040 m = 17040 ÷ 1000 = 17.04 km

(b)
Length of the trail
= 17.04 ÷ 2
= 8.52 km

Answer(s): (a) 17.04 km; (b) 8.52 km