Is the Lift Safe to Use?

Question:

Fred and some other people are in the lift, and their total mass is 565 kg. Fred, who has a mass of 88 kg, gets out of the lift. Is the lift now safe to use?

a) Yes
b) No

Answer:

When the total mass in the lift, including Fred's 88 kg, equals 565 kg, it is over the safety limit of 480 kg. However, when Fred exits, the total mass reduces to 477 kg, which is less than the lift's safety limit, making it safe.

Explanation:

The subject of the question concerns the total mass permitted in a lift for it to be considered safe for use. This limit is stated to be 480 kg. If Fred and some other people are initially in the lift, their total mass adds up to 565 kg. However, if Fred, with a mass of 88 kg, exits the lift, then the total mass in the lift becomes 565 - 88 = 477 kg. Therefore, with Fred exiting the lift, the total mass in the lift is now within the safe limit. So the answer is a) Yes, the lift is now safe to use.