At 10 a.m., Betty and Xuan raced off together from the starting point of a track. Betty ran at an average speed of 1 m/s. Xuan ran at an average speed of 3 m/s. Upon reaching the end of the track, Xuan rested for 5 minutes. She then immediately ran back along the same route at 3 m/s. At 10.30 a.m., Betty met Xuan.
- 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 10.30 a.m. = 30 min
Duration that Betty ran = 30 min
Duration that Xuan ran = 30 - 5 = 25 min
1 min = 60 s
25 min = 25 x 60 = 1500 s
30 min = 30 x 60 = 1800 s
Distance that Betty ran
= 1 x 1800
= 1800 m
Distance that Xuan ran
= 3 x 1500
= 4500 m
Distance that Betty and Xuan ran
= 1800 + 4500
= 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