At 10 a.m., Risa and Joelle raced off together from the starting point of a pathway. Risa ran at an average speed of 3 m/s. Joelle ran at an average speed of 4 m/s. Upon reaching the end of the pathway, Joelle rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 10.30 a.m., Risa met Joelle.

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 10 a.m. to 10.30 a.m. = 30 min

Duration that Risa ran = 30 min
Duration that Joelle ran = 30 -  3 = 27 min

1 min = 60 s

27 min = 27 x 60 = 1620 s
30 min = 30 x 60 = 1800 s

Distance that Risa ran
= 3 x 1800
= 5400 m

Distance that Joelle ran
= 4 x 1620
= 6480 m

Distance that Risa and Joelle ran
= 5400 + 6480
= 11880 m

1000 m = 1 km

11880 m = 11880 ÷ 1000 = 11.88 km

(b)
Length of the trail
= 11.88 ÷ 2
= 5.94 km

Answer(s): (a) 11.88 km; (b) 5.94 km