Texas Instruments TI-92 Owners Manual - Page 424

Simulation of Sampling without Replacement This activity simulates drawing different colored balls from an urn without replacing them. Detailed information about the steps used in this example can be found in Chapter 17: Programming. Sampling-withoutReplacement Function Sampling without Replacement In the Program Editor, define drawball() as a function that can be called with two parameters. The first parameter is a list where each element is the number of balls of a certain color. The second parameter is the number of balls to select. This function returns a list where each element is the number of balls of each color that were selected. :drawball(urnlist,drawnum) :Func :Local templist,drawlist,colordim, numballs,i,pick,urncum,j :If drawnum>sum(urnlist) :Return "too few balls" :dim(urnlist)! colordim :urnlist! templist :newlist(colordim)! drawlist :For i,1,drawnum,1 :sum(templist)! numballs :rand(numballs)! pick :For j,1,colordim,1 :cumSum(templist)! urncum (continued in next column) :If pick  urncum[j] Then :drawlist[j]+1! drawlist[j] :templist[j]ì 1! templist[j] :Exit :EndIf :EndFor :EndFor :Return drawlist :EndFunc Suppose an urn contains n1 balls of a color, n2 balls of a second color, n3 balls of a third color, etc. Simulate drawing balls without replacing them. 1. Enter a random seed using the RandSeed command. 2. Assuming the urn contains 10 red balls and 25 white balls, simulate picking 5 balls at random from the urn without replacement. Enter drawball({10,25},5). Result: 2 red balls and 3 white balls. Chapter 23: Activities 407