Question

There are 10 people in a lift. These 10 people have a mean weight of 79.2kg. 3 of these people get out of the lift. These 3 people have a mean weight of 68kg. Work our the mean weight of the 7 people left in the lift

Answer 1

84kg

Explanation:

10*79.2kg=792kg the weight of the 10 people

3*68kg=204kg the weight of the 3 people who get out of the lift

792kg-204kg=588kg the weight of the 7 people left in the lift

so, the mean weight of the 7 people left in the lift=588kg:7=84 kg