# TI-83 Instructions

## Computing Binomial Probabilities

- Binomial Probability of a Single Individual Value of
*X*
- Press
`2nd DISTR`

. The `DISTR`

menu titles appear. The menu title `DISTR`

is highlighted.
- Scroll down to select
`binompdf`

, the 10th item. (Or press `0`

and skip the next step.)
- Press
`ENTER`

. The phrase `binompdf(`

appears in the display.
- Enter the value of
*n* (the number of trials).
- Press comma.
- Enter the value of
*p* (the probability of success).
- Press comma.
- Enter the value of
*X* (the number of successes for this event).
- Press
`)`

(close parenthesis).
- Press
`ENTER`

. The binomial probability appears in the display.

- Binomial Probability of Several Individual Values of
*X*
- Method 1
- Store the individual values of
*X* in list `L`_{1}

.
- Follow the above instructions, except for step 8.
- In Step 8, instead of entering the value of
*X*, enter `L`_{1}

.
- The result is a list of the individual binomial probabilities corresponding to the values of
*X*.

- Method 2
- Follow the instructions to find the probability of one of the values of
*X*.
- Press
`2nd ENTRY`

. The previous expression (not the answer) appears in the display. It is editable (but not edible).
- Use the left and right arrow keys to move the cursor back to the value of
*X* in the expression `binompdf(`*n*, *p*, *x*)

.
- Press
`DEL`

. The old value is gone.
- Press
`2nd INS`

. The cursor changes shape. The new shape indicates that the calculator is in "insertion" mode.
- Enter the new value of
*X*.
- Press
`ENTER`

. The binomial probability of the new value of *X* appears in the display.
- Repeat this steps for each of the remaining values of
*X*.

- Cumulative Binomial Probabilities for Ranges of Values of
*X*
- Case 1: When the event is
*X* ≤ a.
- Press
`2nd DISTR`

. The `DISTR`

menu titles appear. The menu title `DISTR`

is highlighted.
- Scroll down to select the
`binomcdf`

, the 11th item. (Or press `ALPHA A `

and skip the next step.)
- Press
`ENTER`

.
- Enter the value of
*n* (the number of trials).
- Press comma.
- Enter the value of
*p* (the probability of success).
- Press comma.
- Enter the value of
*a*.
- Press
`)`

(close parenthesis).
- Press
`ENTER`

. The binomial probability *P*(*X* ≤ *a*) appears in the display.

- Case 2: When the event is
*X* ≥ *a*.
- Use the above instructions to compute
*P*(*X* ≤ *a* − 1).
- Subtract the result from 1. The new result is
*P*(*X* ≤ *a*).

- Case 3: When the event is
*a* ≤ *X* ≤ *b*.
- Use the above instructions to compute
*P*(*X* ≤ *b*).
- Use the above instructions to compute
*P*(*X* ≤ *a* − 1).
- Subtract
*P*(*X* ≤ *a* − 1) from *P*(*X*≤ *b*). The result is *P*(*a* ≤ *X* ≤ *b*).