At 7 a.m., Yen and Usha raced off together from the starting point of a course. Yen ran at an average speed of 1 m/s. Usha ran at an average speed of 4 m/s. Upon reaching the end of the course, Usha rested for 6 minutes. She then immediately ran back along the same route at 4 m/s. At 7.30 a.m., Yen met Usha.
- 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 7.30 a.m. = 30 min
Duration that Yen ran = 30 min
Duration that Usha ran = 30 - 6 = 24 min
1 min = 60 s
24 min = 24 x 60 = 1440 s
30 min = 30 x 60 = 1800 s
Distance that Yen ran
= 1 x 1800
= 1800 m
Distance that Usha ran
= 4 x 1440
= 5760 m
Distance that Yen and Usha ran
= 1800 + 5760
= 7560 m
1000 m = 1 km
7560 m = 7560 ÷ 1000 = 7.56 km
(b)
Length of the trail
= 7.56 ÷ 2
= 3.78 km
Answer(s): (a) 7.56 km; (b) 3.78 km