At 11 a.m., Irene and Fiona raced off together from the starting point of a course. Irene ran at an average speed of 3 m/s. Fiona ran at an average speed of 4 m/s. Upon reaching the end of the course, Fiona rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 11.25 a.m., Irene met Fiona.

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 11.25 a.m. = 25 min

Duration that Irene ran = 25 min
Duration that Fiona ran = 25 -  4 = 21 min

1 min = 60 s

21 min = 21 x 60 = 1260 s
25 min = 25 x 60 = 1500 s

Distance that Irene ran
= 3 x 1500
= 4500 m

Distance that Fiona ran
= 4 x 1260
= 5040 m

Distance that Irene and Fiona ran
= 4500 + 5040
= 9540 m

1000 m = 1 km

9540 m = 9540 ÷ 1000 = 9.54 km

(b)
Length of the trail
= 9.54 ÷ 2
= 4.77 km

Answer(s): (a) 9.54 km; (b) 4.77 km