This triangular distribution has a triangular form. Starting with the lower limit a it increases linearly to peak at m. It then decreases linearly to the upper limit at b. The slopes d and e are computed to satisfy the conditions at the left. m is the mode of the distribution.

Example: : A computer is shipped with several identical parts. A company that assembles computers is interested in the distribution of the number of parts required. The computer has at least one of the part and no more than 6. A production supervisor estimates that most computers require two parts. The only information we have is the range of the random variable and its mode (the most likely number). A reasonable estimate for the distribution of parts is the triangular distribution.

The distribution is computed at the left. The add-in has computed the slopes that are shown as the first and last values of the distribution.

d=0.143 and e=0.057.

The mean and variance of this distribution are respectively 3 and 2. The nonzero digits shown as the least significant digits on the figure are due to numerical error.