At 8 a.m., Erika and Kimberly raced off together from the starting point of a course. Erika ran at an average speed of 2 m/s. Kimberly ran at an average speed of 4 m/s. Upon reaching the end of the course, Kimberly rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 8.45 a.m., Erika met Kimberly.

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 8 a.m. to 8.45 a.m. = 45 min

Duration that Erika ran = 45 min
Duration that Kimberly ran = 45 -  4 = 41 min

1 min = 60 s

41 min = 41 x 60 = 2460 s
45 min = 45 x 60 = 2700 s

Distance that Erika ran
= 2 x 2700
= 5400 m

Distance that Kimberly ran
= 4 x 2460
= 9840 m

Distance that Erika and Kimberly ran
= 5400 + 9840
= 15240 m

1000 m = 1 km

15240 m = 15240 ÷ 1000 = 15.24 km

(b)
Length of the trail
= 15.24 ÷ 2
= 7.62 km

Answer(s): (a) 15.24 km; (b) 7.62 km