At 7 a.m., Mary and Emma raced off together from the starting point of a track. Mary ran at an average speed of 1 m/s. Emma ran at an average speed of 2 m/s. Upon reaching the end of the track, Emma rested for 4 minutes. She then immediately ran back along the same route at 2 m/s. At 7.45 a.m., Mary met Emma.
- 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 7 a.m. to 7.45 a.m. = 45 min
Duration that Mary ran = 45 min
Duration that Emma ran = 45 - 4 = 41 min
1 min = 60 s
41 min = 41 x 60 = 2460 s
45 min = 45 x 60 = 2700 s
Distance that Mary ran
= 1 x 2700
= 2700 m
Distance that Emma ran
= 2 x 2460
= 4920 m
Distance that Mary and Emma ran
= 2700 + 4920
= 7620 m
1000 m = 1 km
7620 m = 7620 ÷ 1000 = 7.62 km
(b)
Length of the trail
= 7.62 ÷ 2
= 3.81 km
Answer(s): (a) 7.62 km; (b) 3.81 km