Using random numbers for simulations

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- User manual (382 pages) ,
- Quick start manual (60 pages) ,
- Instruction manual (8 pages)

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HP 35s Using random numbers for simulations

Answer:

The first three random numbers are in the range 0.5 <= random number <1, and therefore equate to the

result "heads." The fourth random number is in the range 0 <= random number < 0.5, and is therefore a

result of "tails." Figures 1 through 4 show the display assuming algebraic mode.

Example 2: Nelson's Newstand sells newspapers and has experienced demand for newspapers as follows over the last

50 days: 10 newspapers on 5 of the days; 15 newspapers on 20 of the days; 20 newspapers on 15 of the

days; and 25 newspapers on 10 of the days. Using random numbers and an initial seed of 0.234567,

simulate demand for the next 4 days.

Solution:

The first step will be to translate the past demand into ranges for our random numbers for the simulation.

Out of past 50 days, demand was 10 on 5 of these days, or 10% of the time. Out of the past 50 days,

demand was 15 on 20 of these days, or 40% of the time. Out of the past 50 days, demand was 20 on 15 of

these days, or 30% of the time. Finally, out of the past 50 days, demand was 25 on 10 of the days, or 20%

of the time. This information can be summarized in a table as shown below.

Demand

10

15

20

25

Next, we need to assign a range for each level of demand that corresponds to the relative probability for

that demand. It is this range that will be used to classify each random number as a specific simulated

demand.

Demand

10

15

20

25

Note that each range corresponds to the probability of each outcome (the range between 0.1 and 0.5 is

40% of the possible outcomes of the random numbers and therefore reflects the 40% chance that a

demand of 15 will occur). Store the initial seed and then generate the five random numbers. Evaluate each

random number as it is generated.

In RPN mode:

In algebraic mode: ¹

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Probability

0.1

0.4

0.3

0.2

Probability

0.1

0.0 < random number <= 0.1

0.4

0.1 < random number <= 0.5

0.3

0.5 < random number <= 0.8

0.2

0.8 < random number < 1.0

¹

- 3 -

Figure 4

Range

HP 35s Using random numbers for simulations - Version 1.0

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