Before any statistical calculations, you must press The Mode Key: Row 1 Column 2  The Decimal Point Key: Row 7 Column 2 for one-variable statistics mode.

The position of the graphically represented keys can be found by moving your mouse on top of the graphic.

Turn your calculator on
Flick the switch on top to the right.
Clearing the memory
Turn the calculator off and then on. (To turn off the calculator, flick the switch to the left.

 

Entering data
one variable
Press  The Mode Key: Row 1 Column 2  The Decimal Point Key: Row 7 Column 2  (to get into one-variable statistics mode).  Type in first number.  Press The M-Plus Key: Row 7 Column 5.  Type in second number.  Press The M-Plus Key: Row 7 Column 5.  Continue until all the data has been entered.
two variables
The Casio fx550s cannot do two-variable statistics.

 

Calculating one-variable statistics

To get into one-variable statistics mode, press  The Mode Key: Row 1 Column 2  The Decimal Point Key: Row 7 Column 2.
mean
Press Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Seven Key: Row 4 Column 1 (x).
standard deviation for populations (s or sn)
Press Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Eight Key: Row 4 Column 2 (sn).
standard deviation for samples (s or sn-1)
Press Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Nine Key: Row 4 Column 3 (sn-1 ).

Calculating combinations and permutations
combinations (nCr)
Enter the n value.  Press Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Divided By Key: Row 5, Column 5 (you should see nCr above the key).  Enter the r value, then The Equals Key: Row 7 Column 4.
permutations (nPr)
Enter the n value.  Press Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Times Key: Row 5, Column 4 (you should see nPr above the key).  Enter the r value, then The Equals Key: Row 7 Column 4.

 

Turning the calculator off
Flick the switch at the top to the left.

 

Worked Out Examples

In the following examples, we list the exact key sequence used to find the answer.  We list the keys by the main symbol on the key.  In parentheses we include a helpful mnemonic, e.g. (ex).


A: What is the mean and standard deviation of the following list of numbers?

15      16      20      21

1: Clear Memory  Turn calculator off and then on.
2: Enter the data: The Mode Key: Row 1 Column 2 The Decimal Point Key: Row 7 Column 2 The One Key: Row 6 Column 1 The Five Key: Row 5 Column 2 The M-Plus Key: Row 7 Column 5 The One Key: Row 6 Column 1 The Six Key: Row 5 Column 3 The M-Plus Key: Row 7 Column 5 The Two Key: Row 6 Column 2 The Zero Key: Row 7 Column 1 The M-Plus Key: Row 7 Column 5 The Two Key: Row 6 Column 2 The One Key: Row 6 Column 1 The M-Plus Key: Row 7 Column 5
3: Compute the mean  Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Seven Key: Row 4 Column 1 (x)
4: Compute the standard deviation (population):  Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Eight Key: Row 4 Column 2 (sn)
5: Compute the standard deviation (sample):  Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Nine Key: Row 4 Column 3 ( sn-1 )


    You should get a mean of 18, population standard deviation of 2.549509757, and a sample standard deviation of 2.943920289.

C: Find 10C6 and 9P5.
1: Compute 10C6  The One Key: Row 6 Column 1 The Zero Key: Row 7 Column 1 Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Divided By Key: Row 5, Column 5 (nCr ) The Six Key: Row 5 Column 3 The Equals Key: Row 7 Column 4
2: Compute 9P5  The Nine Key: Row 4 Column 3 Inverse Key: Row 1 Column 1 (key is blank, inv in writtten above the key) The Times Key: Row 5, Column 4 (nPr ) The Five Key: Row 5 Column 2 The Equals Key: Row 7 Column 4


You should get 10C6 = 210 and 9P5= 15120.

For more information, consult a manual.

Click here for the sample problem set.

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