At 11 a.m., Irene and Mary raced off together from the starting point of a pathway. Irene ran at an average speed of 2 m/s. Mary ran at an average speed of 3 m/s. Upon reaching the end of the pathway, Mary rested for 6 minutes. She then immediately ran back along the same route at 3 m/s. At 11.30 a.m., Irene met Mary.

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 11.30 a.m. = 30 min

Duration that Irene ran = 30 min
Duration that Mary 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 Irene ran
= 2 x 1800
= 3600 m

Distance that Mary ran
= 3 x 1440
= 4320 m

Distance that Irene and Mary ran
= 3600 + 4320
= 7920 m

1000 m = 1 km

7920 m = 7920 ÷ 1000 = 7.92 km

(b)
Length of the trail
= 7.92 ÷ 2
= 3.96 km

Answer(s): (a) 7.92 km; (b) 3.96 km