Final answer:
The average speed of the lift is 1.33 meters per second, calculated by dividing the total distance of 20 meters by the total time of 15 seconds.
Step-by-step explanation:
To calculate the average speed of the lift, we need to consider the total distance traveled and the total time taken. Since the lift goes from the ground floor to the fourth floor without stopping, and the height of each floor is 5 meters, the total distance (D) the lift travels is 4 floors × 5 meters/floor, which equals 20 meters.
The total time (t) taken is given as 15 seconds. The formula for average speed (v) is v = D / t. Substituting the values we have, the average speed of the lift is v = 20 meters / 15 seconds, which equals 1.33 meters per second.