Filter
Top Products
Binomial Probabilities
The command for computing binomial probabilities is binompdf( , which is located on the
DISTR page (which is found in yellow above the fourth key in the fourth row).
To find the probability of x successes out of n trials, each with probability p of success, type
binompdf(n, p, x).
Example: VCR’s
Suppose that 5% of all VCR’s manufactured by an electronics company are defective. Three
VCR’s are selected at random. What is the probability that exactly one of them is defective?
Press the 2
nd
key and then press the VARS key
to get to the DISTR page.
Press the 0 number key to get the binompdf( function.
After binompdf( appears on the screen, type in 3, .05, 1).
Press the ENTER key.
The result is 0.135375 or ≈ 13.5%.
Cumulative Binomial Probabilities
Sometimes rather than wanting to find the probability that a binomial random number is a single
value, we would rather find the probability that it falls up to and including a certain value. The
cumulative binomial probability function can help us do so.
To find the probability that a binomial random number takes values up to and including a certain
value x with number of trials n and probability of success on any given single trial p we use the
binomcdf( .
Example: Deliveries
At the Express House Delivery Service, providing high-quality service to customers is the top
priority of the management. The company guarantees a refund of all charges if a package it is
delivering does not arrive at its destination by the specified time. It is known from past data that
despite all efforts, 7% of the packages mailed through this company do not arrive at their
destinations within the specified time. Suppose a corporation mails 10 packages through Express
House Delivery Service on a certain day.
35