At 10 a.m., Julie and Mary raced off together from the starting point of a track. Julie ran at an average speed of 1 m/s. Mary ran at an average speed of 4 m/s. Upon reaching the end of the track, Mary rested for 5 minutes. She then immediately ran back along the same route at 4 m/s. At 10.25 a.m., Julie met Mary.
- Find the total distance covered by the two runners when they met each other. Express your answer in km.
- Find the length of the trail in km.
(a)
From 10 a.m. to 10.25 a.m. = 25 min
Duration that Julie ran = 25 min
Duration that Mary ran = 25 - 5 = 20 min
1 min = 60 s
20 min = 20 x 60 = 1200 s
25 min = 25 x 60 = 1500 s
Distance that Julie ran
= 1 x 1500
= 1500 m
Distance that Mary ran
= 4 x 1200
= 4800 m
Distance that Julie and Mary ran
= 1500 + 4800
= 6300 m
1000 m = 1 km
6300 m = 6300 ÷ 1000 = 6.3 km
(b)
Length of the trail
= 6.3 ÷ 2
= 3.15 km
Answer(s): (a) 6.3 km; (b) 3.15 km