At 8 a.m., Mary and Eva raced off together from the starting point of a route. Mary ran at an average speed of 2 m/s. Eva ran at an average speed of 4 m/s. Upon reaching the end of the route, Eva rested for 3 minutes. She then immediately ran back along the same route at 4 m/s. At 8.45 a.m., Mary met Eva.
- 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 Mary ran = 45 min
Duration that Eva ran = 45 - 3 = 42 min
1 min = 60 s
42 min = 42 x 60 = 2520 s
45 min = 45 x 60 = 2700 s
Distance that Mary ran
= 2 x 2700
= 5400 m
Distance that Eva ran
= 4 x 2520
= 10080 m
Distance that Mary and Eva ran
= 5400 + 10080
= 15480 m
1000 m = 1 km
15480 m = 15480 ÷ 1000 = 15.48 km
(b)
Length of the trail
= 15.48 ÷ 2
= 7.74 km
Answer(s): (a) 15.48 km; (b) 7.74 km