At 11 a.m., Zara and Esther raced off together from the starting point of a track. Zara ran at an average speed of 1 m/s. Esther ran at an average speed of 2 m/s. Upon reaching the end of the track, Esther rested for 5 minutes. She then immediately ran back along the same route at 2 m/s. At 11.40 a.m., Zara met Esther.

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 11 a.m. to 11.40 a.m. = 40 min

Duration that Zara ran = 40 min
Duration that Esther ran = 40 -  5 = 35 min

1 min = 60 s

35 min = 35 x 60 = 2100 s
40 min = 40 x 60 = 2400 s

Distance that Zara ran
= 1 x 2400
= 2400 m

Distance that Esther ran
= 2 x 2100
= 4200 m

Distance that Zara and Esther ran
= 2400 + 4200
= 6600 m

1000 m = 1 km

6600 m = 6600 ÷ 1000 = 6.6 km

(b)
Length of the trail
= 6.6 ÷ 2
= 3.3 km

Answer(s): (a) 6.6 km; (b) 3.3 km