Question

The mean weight of 25 students in a class is 58 kg. The mean weight of a second class of 29 students is 62 kg. How do you find the mean weight of all the students?

Answer 1

The mean or average weight of all the students is 60.1 kg rounded to the nearest tenth.

Explanation:

This is a weighted average problem.

The formula for determining a weighted average is:

`color(red)(w = ((n_1 xx a_1) + (n_2 xx a_2))/(n_1 + n_2))`

Where `w` is the weighted average,

`n_1` is the number of objects in the first group and `a_1` is the average of the first group of objects.

`n_2` is the number of objects in the second group and `a_2` is the average of the second group of objects.

We were given `n_1` as 25 students, `a_1` as 58 kg, `n_2` as 29 students and `a_2` as 62 kg. Substituting these into the formula we can calculate `w`.

`w = ((25 xx 58) + (29 xx 62))/(25 + 29)`

`w = (1450 + 1798)/54`

`w = 3248/54`

`w = 60.1`