To estimate how many people live in an apartment based on a survey of 300 people, you'll need the proportion of people who live in apartments from a previous survey or data set.
For instance, if in a previous survey, 40% of the respondents lived in apartments, you would calculate the expected number of people living in apartments in the new survey of 300 as follows:
\[ \text{Expected number of apartment dwellers} = \text{Total surveyed} \times \text{Proportion living in apartments} \] \[ \text{Expected number of apartment dwellers} = 300 \times 0.40 = 120 \]
So, if 40% of people typically live in apartments, you would expect around 120 people out of 300 to live in an apartment. If you have a different percentage, you would just replace 0.40 with that value.