factorial symbol can also be found in the MATH PRB menu.
example: Find B (15, .3, 5). That is, find P (X = 5) for a 15 trials of a binomial random variable
X that succeeds with probability 0.3.
solution:(On the TI-83/84, can be foundin the MATH PRB menu. To get , enter (^15) n Cr 5. )
Calculator Tip: On the TI-83/84, the solution to the previous example is given by
binompdf(15,0.3,5) . The binompdf function is found in the DISTR menu of the calculator. The
syntax for this function is binompdf(n, p, x) . The function binomcdf(n, p, x) = P(X = 0) + P(X
= 1) + ... P(X = x ). That is, it adds up the bino-mial probabilities from n = 0 through n = x . You must
remember the “npx” order—it’s not optional. Try a mnemonic like “never play xylophone.”
example: Consider once again our free-throw shooter (Dolores) from the earlier example.
Dolores is a 65% free-throw shooter and each shot is independent. If X is the count of free
throws made by Dolores, then X has B (10, 0.65) if she shoots 10 free throws. What is P (X =
7)?
solution:
example: What is the probability that Dolores makes no more than 5 free throws? That is, what is
P (X ≤ 5)?
solution: