On a 120 km trip a motorist travels 60 km at 60 km/h. How fast must the motorist go for the next 60km in order to average 120km/h for the whole trip?
i have attempted this question, yet the answers say it is impossible.
Speed is distance traveled over time, or
v = d/t
Let x = time needed for the next 60 km
120 km/hr (average) = [(speed1) + (speed2)] / 2
120 = (60 + (60/t)) / 2
240 = 60 + 60/t
60/t = 240 - 60
60/t = 180 km/hr (speed2)
time needed to achieve this speed is
t = 60/180 = 1/3 hr
2 hours
To solve this problem, let's break it down and find the missing information. We are given that the total trip distance is 120 km, and the distance covered at a speed of 60 km/h is 60 km.
Let's use the formula: Average Speed = Total Distance ÷ Total Time.
We know the total distance is 120 km, and we can calculate the total time by dividing the distance by the speed: Total Time = 60 km ÷ 60 km/h = 1 hour.
Now, let's find out how much time is left for the second part of the trip. Since the total time for the entire trip is 1 hour and we have already spent 1 hour on the first part, there is no time left for the second part.
Since there is no time left to cover the remaining 60 km, it is impossible to achieve an average speed of 120 km/h for the whole trip.
Therefore, the answers that say it is impossible are correct.