At 11 a.m., Kathy and Usha raced off together from the starting point of a course. Kathy ran at an average speed of 1 m/s. Usha ran at an average speed of 2 m/s. Upon reaching the end of the course, Usha rested for 5 minutes. She then immediately ran back along the same route at 2 m/s. At 11.45 a.m., Kathy 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 Kathy ran = 45 min
Duration that Usha ran = 45 -  5 = 40 min

1 min = 60 s

40 min = 40 x 60 = 2400 s
45 min = 45 x 60 = 2700 s

Distance that Kathy ran
= 1 x 2700
= 2700 m

Distance that Usha ran
= 2 x 2400
= 4800 m

Distance that Kathy and Usha ran
= 2700 + 4800
= 7500 m

1000 m = 1 km

7500 m = 7500 ÷ 1000 = 7.5 km

(b)
Length of the trail
= 7.5 ÷ 2
= 3.75 km

Answer(s): (a) 7.5 km; (b) 3.75 km