Texas Instruments TI-92 Getting Started page 34

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Graphing Technology Guide: TI-92
Figure 5.93 shows rectangular coordinates of the cursor's location on the graph. You may sometimes wish to trace
along the curve and see polar coordinates of the cursor's location. The first line of the Graph Format menu (Figure
5.24) has options for displaying the cursor's position in rectangular (RECT) or polar (POLAR) form.
Figure 5.93: Polar graph of r = 4 sin θ
5.9 Probability
5.9.1 Random Numbers: The command rand( generates numbers. You will find this command in the Probability
sub-menu of the MATH menu in the Home screen. Press 2nd MATH 7[Probability] 4[rand(] ) ENTER to generate
a random number between 0 and 1. Press ENTER to generate another number; keep pressing ENTER to generate
more of them.
If you need a random number between, say, 0 and 10, then press 10 2nd MATH 7[Probability] 4[rand(] ) ENTER.
To get a random number between 5 and 15, press 5 + 10 2nd MATH 7[Probability] 4[rand(] )ENTER.
If you need the random number to be an integer between 1 and 10 (inclusive), press 2nd MATH 7[Probability]
4[rand(] 10) ENTER. For a random negative integer between –1 and –10 (inclusive), press 2nd MATH
7[Probability] 4[rand(] (-) 10) ENTER
5.9.2 Permutations and Combinations: To calculate the number of permutations of 12 objects taken 7 at a time,
P , press 2nd MATH 7[Probability] 2[nPr(] 12 , 7) ENTER (Figure 5.94). Thus P = 3,991,680.
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Figure 5.94: P and C
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For the number of combinations of 12 objects taken 7 at a time, C , press 2nd MATH 7[Probability] 3[nCr] 12 ,
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7) ENTER (Figure 5.94). Thus C = 792.
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5.9.3 Probability of Winning: A state lottery is configured so that each player chooses six different numbers from 1
to 40. If these six numbers match the six numbers drawn by the State Lottery Commission, the player wins the top
prize. There are C ways for the six numbers to be drawn. If you purchase a single lottery ticket, your probability
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of winning is 1 in C . Press 1 ÷ 2nd MATH 7[Probability] 3[nCr] 40 , 6 ) ENTER to calculate your chances, but
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don't be disappointed.
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