The command has been programmed so that if you do not specify a mean and standard deviation, it will default to the standard normal curve, with \(µ = 0\) and \(σ = 1\). Press to select the ‘normalcdf(’ command, which has a syntax of ‘normalcdf(lower bound, upper bound, mean, standard deviation)’.
The command you will use is found in the DISTR menu, which you can bring up by pressing. Your graphing calculator has already been programmed to calculate probabilities for a normal density curve using what is called a cumulative density function. Technology Note: The 'normalcdf(' Command on TI-83/84 Calculator It's often called 'the bell curve' or the 'the unit normal curve. The standard normal distribution has a mean of 0 and a standard deviation of 1. You can use the mean and standard deviation of the given distribution. The standard normal curve is a bell-shaped curve representing the probability of a normally distributed variable being less than or equal to the given value. When using this command, you do not need to first standardize. The syntax for this command is ‘normalcdf(min, max, µ, σ)’. Use the ‘normalcdf(−2.60, 1.30, 0, 1)’ command, and the calculator will return the result 0.898538.
The probability can also be found using the TI-83/84 calculator.
