Spread, centre, and position. Data sets summarised, measured, and explained one step at a time.
Compute sample or population standard deviation with the variance and every step shown.
Find how many standard deviations a value sits from the mean: z = (x − μ) / σ.
Find the mean, median, mode, and range of a data set with the working shown.
Find the probability of a single event or of two independent events combined.
Compute sample or population variance from a data set, with every step shown.
Find a weighted mean from values and their weights — ideal for grades and ratings.
Count ordered arrangements with nPr = n! / (n − r)!, with the steps shown.
Count unordered selections with nCr = n! / (r!(n − r)!), with the steps shown.
Compute Pearson’s r from paired x and y data to measure linear correlation.
Find a confidence interval for a mean from the sample mean, standard deviation, and size.
Find the percentile rank of a value within a data set, with the working shown.
Find the average (arithmetic mean) of a list of numbers, with the sum and count shown.