At 7 a.m., Usha and Barbara raced off together from the starting point of a track. Usha ran at an average speed of 1 m/s. Barbara ran at an average speed of 2 m/s. Upon reaching the end of the track, Barbara rested for 6 minutes. She then immediately ran back along the same route at 2 m/s. At 7.30 a.m., Usha met Barbara.

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 7.30 a.m. = 30 min

Duration that Usha ran = 30 min
Duration that Barbara ran = 30 -  6 = 24 min

1 min = 60 s

24 min = 24 x 60 = 1440 s
30 min = 30 x 60 = 1800 s

Distance that Usha ran
= 1 x 1800
= 1800 m

Distance that Barbara ran
= 2 x 1440
= 2880 m

Distance that Usha and Barbara ran
= 1800 + 2880
= 4680 m

1000 m = 1 km

4680 m = 4680 ÷ 1000 = 4.68 km

(b)
Length of the trail
= 4.68 ÷ 2
= 2.34 km

Answer(s): (a) 4.68 km; (b) 2.34 km