At 7 a.m., Hilda and Opal raced off together from the starting point of a path. Hilda ran at an average speed of 2 m/s. Opal ran at an average speed of 4 m/s. Upon reaching the end of the path, Opal rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 7.40 a.m., Hilda met Opal.

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 7 a.m. to 7.40 a.m. = 40 min

Duration that Hilda ran = 40 min
Duration that Opal 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 Hilda ran
= 2 x 2400
= 4800 m

Distance that Opal ran
= 4 x 2220
= 8880 m

Distance that Hilda and Opal ran
= 4800 + 8880
= 13680 m

1000 m = 1 km

13680 m = 13680 ÷ 1000 = 13.68 km

(b)
Length of the trail
= 13.68 ÷ 2
= 6.84 km

Answer(s): (a) 13.68 km; (b) 6.84 km