Calculating Average Speed

To calculate the average speed, we need to find the total distance traveled and divide it by the total time taken. In this case, we have four laps with different speeds. Let's calculate the total distance and total time taken for each lap.

Lap 1: Speed = 10 kmph
Lap 2: Speed = 20 kmph
Lap 3: Speed = 40 kmph
Lap 4: Speed = 60 kmph

Calculating Total Distance
To calculate the total distance, we need to know the length of each lap. Let's assume the length of each lap is 'd' kilometers.

Lap 1: Distance = Speed * Time
Distance = 10 kmph * d = 10d km

Lap 2: Distance = Speed * Time
Distance = 20 kmph * d = 20d km

Lap 3: Distance = Speed * Time
Distance = 40 kmph * d = 40d km

Lap 4: Distance = Speed * Time
Distance = 60 kmph * d = 60d km

Now, let's calculate the total distance traveled by adding the distances of all four laps.
Total Distance = 10d + 20d + 40d + 60d = 130d km

Calculating Total Time
To calculate the total time taken, we need to know the time taken to complete each lap. Let's assume the time taken for each lap is 't' hours.

Lap 1: Time = Distance / Speed
Time = (10d km) / (10 kmph) = d hours

Lap 2: Time = Distance / Speed
Time = (20d km) / (20 kmph) = d hours

Lap 3: Time = Distance / Speed
Time = (40d km) / (40 kmph) = d hours

Lap 4: Time = Distance / Speed
Time = (60d km) / (60 kmph) = d hours

Now, let's calculate the total time taken by adding the times of all four laps.
Total Time = d + d + d + d = 4d hours

Calculating Average Speed
Average Speed = Total Distance / Total Time
Average Speed = (130d km) / (4d hours)
Average Speed = 32.5 kmph

So, the correct answer for the average speed is 32.5 kmph, not 20 kmph as mentioned in the question.