EXAMPLE 42Normal probabilities and percentiles using technology

Applying the information on Toyota Camry prices from Example 41, use the TI-83/84, Excel, Minitab, or JMP to find the following:

  1. The proportion of 2015 Camry XLEs costing between $27,000 and $30,000:
  2. The 99th percentile of Camry XLE prices; that is, find the value of , namely, , such that

Solution

The instructions for finding these quantities are given in the Step-by-Step Technology Guide at the end of this section (page 380).

TI-83/84

  1. Figure 55 shows that .
  2. Figure 56 shows that the value for , such that , is given by .
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    Figure 6.57: FIGURE 55 TI-83/84: Finding a probability.
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    Figure 6.58: FIGURE 56 TI-83/84: Finding a value of .

Excel

  1. Excel provides the cumulative probabilities in Figure 57 and in Figure 58. To find , we subtract from :
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    Figure 6.59: FIGURE 57 Excel: .

    376

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    Figure 6.60: FIGURE 58 Excel: .
  2. Excel provides the result shown in Figure 59:
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    Figure 6.61: FIGURE 59 Excel: Finding a value of .

Minitab

  1. Similar to Excel, Minitab asks you to take the difference of two cumulative probabilities: in Figure 60 and in Figure 61:
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    Figure 6.62: FIGURE 60 Minitab: .
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    Figure 6.63: FIGURE 61 Minitab: .
  2. The results are given in Figure 62:
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    Figure 6.64: FIGURE 62 Minitab: Finding a value of .

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JMP

  1. JMP also asks you to take the difference of two cumulative probabilities: in Figure 63 and in Figure 64:
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    Figure 6.65: FIGURE 63 JMP: .
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    Figure 6.66: FIGURE 64 JMP: .
  2. The results are given in Figure 65:
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    Figure 6.67: FIGURE 65 JMP: Finding a value of .