Instruction of online calculator

Z for 95 Confidence Interval Calculator

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Input Data
Output

Introduction

Confidence intervals (CI) are statistical tools that provide a range within which the true population parameter is likely to fall. When calculating a 95% Confidence Interval using the Z-score, we assume the data follows a normal distribution. The Z-score for a 95% Confidence Interval is 1.96, which corresponds to the critical value for this confidence level.

Numerical Example

Let’s consider the following sample data:

  • Sample Mean = 50
  • Standard Deviation = 4
  • Sample Size = 100

Steps to calculate the 95% Confidence Interval:

  1. Formula:

      2. Substitute the values:

This means there is a 95% probability that the true population mean falls between 49.216 and 50.784.

How to Use the Calculator

  1. Input Your Data: Enter the sample mean, standard deviation, and sample size into the appropriate fields of the calculator.

      2. Choose Confidence Level: Select “95%” as the confidence level; this ensures the Z-score used will be 1.96.

      3. Click Calculate: Press the “Calculate” button to generate the upper and lower bounds of the confidence interval.

      4. Review the Results: The calculator will display the confidence interval range, helping you understand the likely range for the population parameter.

Z for 95 Confidence Interval Calculator