?a car is moving on a straight road covers one third of the distance w...
**Average Speed Calculation:**
To calculate the average speed of the car, we need to consider the total distance traveled and the total time taken.
**Step 1: Calculate the total distance:**
Let's assume the total distance covered by the car is D.
According to the question, the car covers one-third of the distance with a speed of 20 km/h. So, the distance covered at 20 km/h can be calculated as:
Distance1 = (1/3) * D
The remaining distance is covered at a speed of 60 km/h, which can be calculated as:
Distance2 = (2/3) * D
Therefore, the total distance covered is:
Total distance = Distance1 + Distance2 = (1/3) * D + (2/3) * D = D
So, the total distance covered by the car is D.
**Step 2: Calculate the total time taken:**
To find the average speed, we need to calculate the total time taken by the car.
The time taken to cover Distance1 at a speed of 20 km/h can be calculated using the formula:
Time1 = Distance1 / Speed1
Given that Speed1 = 20 km/h and Distance1 = (1/3) * D, we can substitute these values into the formula:
Time1 = [(1/3) * D] / 20
Similarly, the time taken to cover Distance2 at a speed of 60 km/h can be calculated as:
Time2 = Distance2 / Speed2
Given that Speed2 = 60 km/h and Distance2 = (2/3) * D, we can substitute these values into the formula:
Time2 = [(2/3) * D] / 60
Therefore, the total time taken is:
Total time = Time1 + Time2 = [(1/3) * D] / 20 + [(2/3) * D] / 60
**Step 3: Calculate the average speed:**
The average speed can be calculated by dividing the total distance by the total time taken:
Average speed = Total distance / Total time
Substituting the values of the total distance and total time, we get:
Average speed = D / [(1/3) * D / 20 + (2/3) * D / 60]
Simplifying the equation:
Average speed = 1 / [(1/3) / 20 + (2/3) / 60]
Now, let's simplify the expression within the brackets:
Average speed = 1 / (1/60 + 2/180)
Average speed = 1 / (3/180 + 2/180)
Average speed = 1 / (5/180)
Average speed = 180 / 5
Average speed = 36 km/h
Therefore, the average speed of the car is 36 km/h.
?a car is moving on a straight road covers one third of the distance w...
36kmph
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