At 7 a.m., Risa and Zara raced off together from the starting point of a route. Risa ran at an average speed of 1 m/s. Zara ran at an average speed of 2 m/s. Upon reaching the end of the route, Zara rested for 3 minutes. She then immediately ran back along the same route at 2 m/s. At 7.45 a.m., Risa met Zara.
- 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 Risa ran = 45 min
Duration that Zara 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 Risa ran
= 1 x 2700
= 2700 m
Distance that Zara ran
= 2 x 2520
= 5040 m
Distance that Risa and Zara ran
= 2700 + 5040
= 7740 m
1000 m = 1 km
7740 m = 7740 ÷ 1000 = 7.74 km
(b)
Length of the trail
= 7.74 ÷ 2
= 3.87 km
Answer(s): (a) 7.74 km; (b) 3.87 km