How it works
For random draws without replacement, expected marked items equal draw count times the marked share of the finite population. This form solves for expected marked quantity; enter the known quantities in Number of draws without replacement, Marked population items, Total population.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Number of draws without replacement | 20 | Formula symbol: draws. Enter a numeric value. Use a whole number. Use a non-negative value. |
| Marked population items | 20 | Formula symbol: marked. Enter a numeric value. Use a whole number. Use a non-negative value. |
| Total population | 100 | Formula symbol: population. Enter a numeric value. Use a whole number. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Number of draws without replacement
- 20
- Marked population items
- 20
- Total population
- 100
Complete example results
- Expected marked quantity
- 4
Reading the result
The result solves for expected marked quantity from the entered quantities. Check the result unit and the formula conditions before using it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
When can I use the expected marked quantity result?
Expectation is neither a realised count nor a probability of a specific outcome. Inverse target counts round up to a minimum integer. Draws and marked items cannot exceed the population.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: math.ucsd.edu