Calculations with the Mean Flashcards

All 4 cards in this deck

What are the steps to find a missing value when you know the mean?

e.g. four numbers have mean $10$; three of them add to $32$

1. Total $=$ mean $\times$ number of values: $10\times4=40$
2. Subtract the values you know: $40-32=8$
3. The missing value is $8$

True or false? The mean of two groups is found by adding the two group means and dividing by 2.

False. That only works if both groups are the same size; otherwise use total of all values ÷ total number of values.

If one value in a data set is replaced by a larger value, what happens to the mean?

The mean increases, because the total increases while the number of values stays the same.

True or false? If you add a new value equal to the current mean, the mean stays the same.

True. The total and the number of values both grow in proportion.