At 9 a.m., Cathy and Rachel raced off together from the starting point of a route. Cathy ran at an average speed of 1 m/s. Rachel ran at an average speed of 2 m/s. Upon reaching the end of the route, Rachel rested for 5 minutes. She then immediately ran back along the same route at 2 m/s. At 9.50 a.m., Cathy met Rachel.

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 Cathy ran = 50 min
Duration that Rachel ran = 50 -  5 = 45 min

1 min = 60 s

45 min = 45 x 60 = 2700 s
50 min = 50 x 60 = 3000 s

Distance that Cathy ran
= 1 x 3000
= 3000 m

Distance that Rachel ran
= 2 x 2700
= 5400 m

Distance that Cathy and Rachel ran
= 3000 + 5400
= 8400 m

1000 m = 1 km

8400 m = 8400 ÷ 1000 = 8.4 km

(b)
Length of the trail
= 8.4 ÷ 2
= 4.2 km

Answer(s): (a) 8.4 km; (b) 4.2 km