At 9 a.m., Sarah and Roshel raced off together from the starting point of a route. Sarah ran at an average speed of 3 m/s. Roshel ran at an average speed of 4 m/s. Upon reaching the end of the route, Roshel rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 9.50 a.m., Sarah met Roshel.

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 Sarah ran = 50 min
Duration that Roshel ran = 50 -  3 = 47 min

1 min = 60 s

47 min = 47 x 60 = 2820 s
50 min = 50 x 60 = 3000 s

Distance that Sarah ran
= 3 x 3000
= 9000 m

Distance that Roshel ran
= 4 x 2820
= 11280 m

Distance that Sarah and Roshel ran
= 9000 + 11280
= 20280 m

1000 m = 1 km

20280 m = 20280 ÷ 1000 = 20.28 km

(b)
Length of the trail
= 20.28 ÷ 2
= 10.14 km

Answer(s): (a) 20.28 km; (b) 10.14 km