NORM.INV in WPS Spreadsheet: Find a Normal Percentile

=NORM.INV(0.95,100,15) returns an independently expected 124.6728044. It finds the value at or below which 95% of a normal model with mean 100 and standard deviation 15 lies. The output is in the measurement’s units, not a probability.

NORM.INV(probability,mean,standard_dev)

All three arguments are required. probability is the lower-tail cumulative probability; use a numeric value strictly between 0 and 1 in this guide. mean is the distribution’s arithmetic mean. standard_dev is its positive standard deviation, not its variance. Use 0.95 or 95%, not the integer 95.

Put 0.95 in B2, 100 in B3 and 15 in B4. Label A2:A4 Probability, Mean minutes and Standard deviation minutes. Enter =NORM.INV(B2,B3,B4) in D2.

Expected output: 124.6728044 minutes. This threshold is a normal-model percentile. It is not a guaranteed maximum processing time or a confidence interval for an estimated mean.

Independent calculation: the standard-normal 95th percentile is 1.64485362695. Multiplying by 15 and adding 100 gives 124.672804404.

The last pair sums to 200. Display rounding may differ; retain the full result in subsequent formulas.

Split the remaining 5% evenly between the tails:

=NORM.INV(0.025,100,15)
=NORM.INV(0.975,100,15)

Expected endpoints: 70.60054023 and 129.39945977 minutes. Using 0.05 and 0.95 instead would give a central 90% interval. These limits describe individual model values under the specified parameters; uncertainty from estimating those parameters is not included.

The official source documents #VALUE! for nonnumeric arguments and #NUM! when standard deviation is zero or negative. Check numeric cell storage and whether a squared variance was supplied accidentally.

Its probability-error bullet is visibly truncated after the argument name. This guide therefore uses only interior probabilities and does not invent an exact endpoint error contract for this identity. The source also contains a self-referential standard-normal link; that is not evidence of another function’s alias status.

The lesson defines the inverse by NORM.DIST(x,mean,standard_dev,TRUE)=probability and says accuracy depends on that calculation. Extreme-tail precision and iteration limits remain untested. If the model is inappropriate for the data, a valid formula still gives an inappropriate threshold.

The official WPS NORM.INV lesson was fetched afresh on October 19, 2026. Its edition banner says WPS Office for Windows Personal. The lesson dates from 2019; it does not establish introduction or retirement dates, exact build coverage, or current Mac, Linux, web and mobile behavior. Examples are independently calculated expectations, not observed WPS outputs. Native execution and genuine current-application screenshots remain unverified.

NORMINV, NORMDIST, STDEV.S. Browse the WPS function library.