At 11 a.m., Opal and Usha raced off together from the starting point of a pathway. Opal ran at an average speed of 1 m/s. Usha ran at an average speed of 4 m/s. Upon reaching the end of the pathway, Usha rested for 6 minutes. She then immediately ran back along the same route at 4 m/s. At 11.45 a.m., Opal met Usha.

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 11.45 a.m. = 45 min

Duration that Opal ran = 45 min
Duration that Usha ran = 45 -  6 = 39 min

1 min = 60 s

39 min = 39 x 60 = 2340 s
45 min = 45 x 60 = 2700 s

Distance that Opal ran
= 1 x 2700
= 2700 m

Distance that Usha ran
= 4 x 2340
= 9360 m

Distance that Opal and Usha ran
= 2700 + 9360
= 12060 m

1000 m = 1 km

12060 m = 12060 ÷ 1000 = 12.06 km

(b)
Length of the trail
= 12.06 ÷ 2
= 6.03 km

Answer(s): (a) 12.06 km; (b) 6.03 km