At 8 a.m., Emma and Julie raced off together from the starting point of a route. Emma ran at an average speed of 2 m/s. Julie ran at an average speed of 4 m/s. Upon reaching the end of the route, Julie rested for 5 minutes. She then immediately ran back along the same route at 4 m/s. At 8.45 a.m., Emma met Julie.
- 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 8 a.m. to 8.45 a.m. = 45 min
Duration that Emma ran = 45 min
Duration that Julie 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 Emma ran
= 2 x 2700
= 5400 m
Distance that Julie ran
= 4 x 2400
= 9600 m
Distance that Emma and Julie ran
= 5400 + 9600
= 15000 m
1000 m = 1 km
15000 m = 15000 ÷ 1000 = 15 km
(b)
Length of the trail
= 15 ÷ 2
= 7.5 km
Answer(s): (a) 15 km; (b) 7.5 km