How Does My TI 84 Do That A guide to using the TI 84 for statistics Austin Peay State University Clarksville Tennessee How Does My TI 84 Do That A guide to using the TI 84 for statistics Table of Contents Understanding the Instructions in this Guide Basic Operations Clearing the memory Arithmetic operations Negative numbers Absolute value Powers and roots Adjusting the window for graphs Probability and Statistics Generating random integers Factorials Permutations Combinations Entering data into a list Box plots Modified box plots Scatter plots xyLine Histograms Normal probability plots 1 variable statistics 2 variable statistics Correlation and regression Graphing the regression line Confidence intervals for proportions Hypothesis testing for proportions Confidence intervals for means Hypothesis testing for means Chi Square Other Sorting lists 2 3 3 3 4 4 5 6 7 7 8 8 9 9 10 10 11 11 12 12 13 14 15 16 18 18 19 21 23 25 1 Understanding the Instructions in this Guide In order to provide consistency in instructions the following conventions will be used to describe procedures indicates a particular key which should be pushed example 2nd indicates the key in the upper left corner of the calculator marked 2nd indicates a name or function associated with a key after the 2nd or Alpha key has been pressed example 2nd Mem indicates student should press the 2nd key first At this point the names or function of the keys are the names printed in blue over the key The student will find Mem printed above the key indicates an item selected from a list example ClrList indicates the students should scroll down the list displayed on the screen and select the item named ClrList Numbers will be shown as just the number without indicating which keys to press in order to enter the number 2nd 2nd Mem ClrList 2 Basic Operations Clearing the memory Sometimes you may find it necessary to clear the memory on your calculator and reset all the defaults Warning doing this will wipe out any stored programs which you may have on your calculator To clear the memory and reset defaults press 2nd Mem Reset All All Memory Reset You will receive a message informing you that the memory has been cleared Arithmetic operations Arithmetic operations are performed using the five gray function keys on the right side of the calculator and Enter and the two parenthesis keys and The calculator performs the calculations inside parentheses prior to the other calculations Keys for arithmetic operations 3 Example To calculate 5 15 3 7 2 press the following keys 5 15 3 7 2 Enter Negative Numbers The TI 84 calculator uses a separate key to denote negative numbers The inverse or negative key is located on the bottom row of the calculator on the right hand side Frequently students mistakenly try to use the inverse key for subtraction this will result in an error Negative key Example to calculate 15 3 press the following keys 15 3 Enter Absolute value To determine the absolute value of a number or calculation press Math Num abs and enter the number or calculation Remember to close the parenthesis before hitting Enter Example to determine the absolute value of 15 3 press the following keys Math Num abs 15 3 Enter 4 Powers and roots The calculator has three keys which are used to calculate powers and roots x2 is used to square a number is used to determine the square root of a number Note the automatically opens a set of parentheses is used to determine any power or root of a number Examples to determine 8 squared press the following keys 8 x2 Enter to determine the square root of 8 press the following keys 2nd 8 Enter to determine the cube root of 8 press the following keys 8 1 3 Enter Note you can also determine roots of numbers by pressing the following keys the root you want Math x the number you wish to determine the root of Enter Example to determine the 4th root of 16 press 4 Math x 16 Enter 5 Adjusting the window for graphs You may change the size scale and resolution of the graphing window in order to change what the calculator displays for a graph or boxplot The features you may change are Xmin the minimum value for x displayed Xmax the maximum value for x displayed Xscl the number of units between index marks on the x axis Ymin the minimum value for y displayed Ymax the maximum value for y displayed Yscl the number of units between index marks on the y axis Xres resolution of the graph You may set this between 1 and 8 At 1 the calculator evaluates and graphs the equation at each pixel At 8 the calculator evaluates and graphs every eighth pixel Cautions The Xscl or Yscl should be proportional to the difference between the min and max for each axis otherwise the index marks may be too close together for effective use Setting the Xres to 1 provides greater resolution but it also slows down the graphing process To change the window settings press Window You may now use the down arrow key to move down the list and make adjustments When you are finished press 2nd Quit 6 Probability and Statistics Generating random integers To generate one random integer press Math PRB randInt the lowest integer you want to generate the highest integer you want to generate Enter Note the RandInt function automatically opens a set of parentheses Example to generate one random integer between 15 and 23 press Math PRB randInt 15 23 Enter To generate multiple random integers with replacement place a comma after the highest integer value and enter the total number of integers you want generated Note since the calculator generates random integers with replacement to generate a list of n distinct random integers you can increase the number of integers generated and select the first n distinct integers Example to generate five distinct random integers between 15 and 23 press Math PRB randInt 15 23 8 Enter In this example the calculator generated the number 23 twice so you would use 23 16 19 and 18 then press the left arrow key to see the next integer which is 21 7 Factorials To calculate a factorial enter the number press Math PRB Enter Example to calculate 4 press 4 Math PRB Enter Permutations To calculate the number of permutations of items taken a given number at a time enter the number of items Math PRB nPr number of items taken at a time Enter Example From 5 people 2 will be selected for positions on a committee 1 as chair the other as secretary You are to determine the number of possible outcomes To calculate press 5 Math PRB nPr 2 Enter 8 Combinations