At 9 a.m., Lynn and Erika raced off together from the starting point of a track. Lynn ran at an average speed of 1 m/s. Erika ran at an average speed of 4 m/s. Upon reaching the end of the track, Erika rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 9.45 a.m., Lynn met Erika.

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 9 a.m. to 9.45 a.m. = 45 min

Duration that Lynn ran = 45 min
Duration that Erika ran = 45 -  3 = 42 min

1 min = 60 s

42 min = 42 x 60 = 2520 s
45 min = 45 x 60 = 2700 s

Distance that Lynn ran
= 1 x 2700
= 2700 m

Distance that Erika ran
= 4 x 2520
= 10080 m

Distance that Lynn and Erika ran
= 2700 + 10080
= 12780 m

1000 m = 1 km

12780 m = 12780 ÷ 1000 = 12.78 km

(b)
Length of the trail
= 12.78 ÷ 2
= 6.39 km

Answer(s): (a) 12.78 km; (b) 6.39 km