Average speed

The car drove from city A to city B at a 40 km/h and back to city A at a speed of 80 km/h. What was the average speed of the car?

Correct answer:

v =  53.3333 km/h

Step-by-step explanation:

$$\begin{gathered} v_1=40\text{ km/h } \\ {v}_2=80\text{ km/h } \\ v=s\mathrm{/}t \\ v={\displaystyle \frac{2\cdot s}{s\mathrm{/}{v}_1+s\mathrm{/}{v}_2}} \\ v={\displaystyle \frac{2}{1\mathrm{/}{v}_1+1\mathrm{/}{v}_2}}={\displaystyle \frac{2}{1\mathrm{/}40+1\mathrm{/}80}}={\displaystyle \frac{160}{3}}=53.3333\text{ km/h} \end{gathered}$$

Try another example

Related math problems and questions:

• Two cities
  The car goes from city A to city B at an average speed of 70 km/h, back at an average speed of 50 km/h. If it goes to B and back at an average speed of 60 km/h, the whole ride would take 8 minutes less. What is the distance between cities A and B?
• Average speed
  The truck drove 1/2 of the way on the highway at 80km/h. The other half of the way 20km/h. Calculate the average speed
• Forth and back
  Car drive from point A to point B at speed 78 km/h and back at 82 km/h. If went there and back at speed 81 km/h journey would take five minutes less. What is the distance between points A and B?
• Car
  The car goes from point A to point B at speed 86 km/h and back 53 km/h. If it goes there and back at speed 67 km/h trip would take 10 minutes shorter. What is the distance between points A and B?
• Two cities
  Cities A and B are 200 km away. At 7 o'clock from city A, the car started at an average speed of 80 km/h, and from B at 45 min later the motorcycle is started at an average speed of 120 km/h. How long will they meet and at what distance from the point A i
• Average
  What is the average speed of the car, where half of the distance covered passed at speed 66 km/h and the other half at 86 km/h.
• Car
  The driver of a car is to get to 608 km distant city. From atlas found that 162 km will have to pass through the cities at average speed 48 km/h. Remainder of the journey pass outside the cities at average speed 116 km/h. Calculate how many hours it will
• Motion
  From two different locations distant 232 km started against car and bus. The car started at 5:20 with average speed 64 km/h. Bus started at 7:30 with average speed 80 km/h. When they meet? How many kilometers went the bus?
• Freight and passenger car
  The truck starts at 8 pm at 30 km/h. Passenger car starts at 8 pm at 40 km/h. Passenger arrives in the destination city 1 hour and 45 min earlier. What is the distance between the city of departure and destination city?
• Company car
  Ms. Vaňková has a company car equipped with a multifunction indicator, on which she can monitor the average petrol consumption during individual rides. During the first ride, mostly in city traffic, it traveled 20.5 km, with an average consumption of 7.8L
• Speed of car
  The car went to a city that was 240 km away. If his speed increased by 8 km/h, it would reach the finish one hour earlier. Determine its original speed.
• Cars speeds
  Distance from city A to city B is 108 km. Two cars were simultaneously started from both places. The speed of a car coming from city A was 2 km/h higher than the second car. What was the speed of each car if they met in 54 minutes?
• Train and car
  The train and the car started at a constant speed to journey. When the train travels 87 km, the car travels 97 km. How many km travels the train when the car travels 87 km?
• Fog
  The car started in fog at speed 30 km/h. After a 12-minute drive, the fog dissipated and the driver drove next 12 minutes distance 17 km. On the last 17 km long again the driving conditions deteriorated and the driver drove the speed of 51 km/h. a) Calcul
• Uphill and downhill
  The cyclist moves uphill at a constant speed of v1 = 10 km/h. When he reaches the top of the hill, he turns and passes the same track downhill at a speed of v2 = 40 km/h. What is the average speed of a cyclist?
• Cars motion
  From point A car start at the speed of 90 km/h. Against it departs from the point B at the same time another car at 60 km/h. For how long and where they met if the distance between A and B is 180 km?
• Driver
  The driver of the supply car reckoned that at the average speed of 72 km/h arrives to the warehouse for 1 1/4 hours. After 30 km however unintentionally drove to the gas station and have ten minutes delay. At what average speed would have to go the rest o