At 8 a.m., Risa and Julie raced off together from the starting point of a pathway. Risa ran at an average speed of 1 m/s. Julie ran at an average speed of 4 m/s. Upon reaching the end of the pathway, Julie rested for 4 minutes. She then immediately ran back along the same route at 4 m/s. At 8.25 a.m., Risa met Julie.

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 8.25 a.m. = 25 min

Duration that Risa ran = 25 min
Duration that Julie 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 Risa ran
= 1 x 1500
= 1500 m

Distance that Julie ran
= 4 x 1260
= 5040 m

Distance that Risa and Julie ran
= 1500 + 5040
= 6540 m

1000 m = 1 km

6540 m = 6540 ÷ 1000 = 6.54 km

(b)
Length of the trail
= 6.54 ÷ 2
= 3.27 km

Answer(s): (a) 6.54 km; (b) 3.27 km