Question

At school there is a group planning the exhibition.

There are 20 people in the group and the mean of their ages is 12 years. Three new people whose ages are 10, 11 and 15 join the group.
How does this affect the mean?

Answer 1

The mean of a group is calculated by adding up all the values in the group and then dividing by the number of values. In this case, the mean age of the original group of 20 people is 12 years. This means that the sum of their ages is 20 * 12 = 240 years.

When three new people with ages 10, 11, and 15 join the group, the total number of people in the group increases to 23. The sum of their ages becomes 240 + 10 + 11 + 15 = 276 years. The new mean age of the group is calculated by dividing the sum of their ages by the number of people in the group: 276 / 23 ≈ 12 years.

So, after three new people join the group, the mean age remains approximately the same at around 12 years.