Calculate the confidence interval of a sample set. Enter the sample number, the sample mean, and standard deviation to calculate the confidence interval.

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## Confidence Interval Formula

The confidence of a sample set can be calculated through the following formula:

**X ± Zs√(n)**

- Where X is the mean
- Z is the Z-Value
- s is the standard deviation
- n is the number of samples

The z-value or z-score can be calculated using the table below.

Confidence Level | Z |

80% | 1.282 |

85% | 1.44 |

90% | 1.645 |

95% | 1.96 |

99% | 2.576 |

99.50% | 2.807 |

99.90% | 3.291 |

## Confidence Interval Definition

A confidence interval is a type of estimate in statistics that shows a possible range of values for an unknown variable or parameter.

## How to calculate a confidence interval?

Time needed: 10 minutes.

How to calculate a confidence interval?

**First, you need to calculate the mean of your sample set.**This can be done by summing the entire set of numbers and then dividing by the total numbers in the sample set. Another word for the mean is average.

**Next, you need to determine the z-score.**This is done through the use of the table above. Simply select the confidence level you wish to calculate the confidence interval at, and use the table to grab the z-value.

**Calculate the standard deviation**Standard Deviation Formula

**Finally, enter the values into the calculator.**Alternatively, you could simply enter the values into the formula and calculate using a normal calculator.

## FAQ

**What is a confidence interval?**

A confidence interval is a type of estimate in statistics that shows a possible range of values for an unknown variable or parameter.

**How do i choose a confidence level?**

A confidence level is going to be chosen based on the statistics and outcomes being analyzed. If you have greater confidence in your data, choosing a higher confidence level.

**Why is the solution two different values?**

A confidence interval is a range of values-based on the mean. As a result, the solution will be both the upper and lower bounds of that range of values.