At 7 a.m., Zara and Irene raced off together from the starting point of a route. Zara ran at an average speed of 1 m/s. Irene ran at an average speed of 4 m/s. Upon reaching the end of the route, Irene rested for 5 minutes. She then immediately ran back along the same route at 4 m/s. At 7.35 a.m., Zara met Irene.

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 7.35 a.m. = 35 min

Duration that Zara ran = 35 min
Duration that Irene ran = 35 -  5 = 30 min

1 min = 60 s

30 min = 30 x 60 = 1800 s
35 min = 35 x 60 = 2100 s

Distance that Zara ran
= 1 x 2100
= 2100 m

Distance that Irene ran
= 4 x 1800
= 7200 m

Distance that Zara and Irene ran
= 2100 + 7200
= 9300 m

1000 m = 1 km

9300 m = 9300 ÷ 1000 = 9.3 km

(b)
Length of the trail
= 9.3 ÷ 2
= 4.65 km

Answer(s): (a) 9.3 km; (b) 4.65 km