A man drives his car for 24 km at a speed of 48 km/h, and for the next 1.5 hours he drives at a speed of 80 km/h. Find his average speed (in km/h) for the entire journey.

Step 1: Calculate the time taken for the first part of the journey

The man drives for 24 km at a speed of 48 km/h. The time taken for this part of the journey can be calculated using the formula:

Time = Distance / Speed

So, Time = 24 km / 48 km/h = 0.5 hours

Step 2: Calculate the total distance covered

The man then drives for another 1.5 hours at a speed of 80 km/h. The distance covered in this part of the journey can be calculated using the formula:

Distance = Speed * Time

So, Distance = 80 km/h * 1.5 hours = 120 km

The total distance covered in the entire journey is the sum of the distances covered in the two parts, which is 24 km + 120 km = 144 km

Step 3: Calculate the total time taken

The total time taken for the journey is the sum of the time taken for the two parts, which is 0.5 hours + 1.5 hours = 2 hours

Step 4: Calculate the average speed

The average speed for the entire journey can be calculated using the formula:

Average Speed = Total Distance / Total Time

So, Average Speed = 144 km / 2 hours = 72 km/h

Therefore, the man's average speed for the entire journey is 72 km/h.