GB-31-05-001 · Combined means

16 students have a mean score of 32. A second group of 9 students has a mean score of 39. Find the mean score for the combined group to 2 decimal places.

Averages: 'Mean' Mean ("TiMoNe" Table) Booklet p. 56

Method

1) Draw TiMoNe table (Mean | Number | Total) for Group A, Group B, Total

2) Multiply Mean × Number for each group

3) Total Mean = Combined Total ÷ Combined Number (NEVER add means!)

Worked Example (GB-31-05-001)

NEVER add or subtract in the Mean column! Multiply Mean × Number = Total.

Group	Mean	Number	Total ( $\text{Mean}\times\text{Number}$ )
Group 1	$32$	$16$	$32 \times 16 = 512$
Group 2	$39$	$9$	$39 \times 9 = 351$
Combined	$863 \div 25$	$25$	$863$

34.52