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A box contains four slips of paper marked \(1,2,3\), and 4\. Two slips are selected without replacement. List the possible values for each of the following random variables: a. \(x=\) sum of the two numbers b. \(y=\) difference between the first and second numbers c. \(z=\) number of slips selected that show an even number d. \(w=\) number of slips selected that show a 4

Short Answer

Expert verified
a. Possible values of \(x\) are 3,4,5,6,7.\nb. Possible values of \(y\) are -3,-2,-1,0,1,2,3.\nc. Possible values of \(z\) are 0,1,2.\nd. Possible values of \(w\) are 0 and 1.

Step by step solution

01

Sum of the two numbers

For part a, the random variable \(x\) is defined as the sum of the two numbers. The two numbers can be any of the four slips, and since they are selected without replacement, the pair of numbers can be: (1,2), (1,3), (1,4), (2,3), (2,4), (3,4). When summed, the possible values are: 3, 4, 5, 5, 6, and 7.
02

Difference between the first and second numbers

For part b, the random variable \(y\) is the difference between the first and second numbers, considering the order. If the first number is smaller than the second, the value will be negative, if not, it will be positive. Therefore, the possible values are: -3, -2, -1, 0, 1, 2, 3.
03

Number of slips selected that show an even number

For part c, the random variable \(z\) is the number of slips selected that show an even number. Since we are selecting 2 slips, we can have 0, 1, or 2 slips showing an even number. Thus, possible values are 0, 1, 2.
04

Number of slips selected that show a 4

For part d, the random variable \(w\) is the number of slips selected that show a 4. Since we are only selecting 2 slips out of a possible 4, and only one of the 4 slips are labelled as '4', the possible values are 0 (if '4' is not selected) and 1 (if '4' is selected). Therefore, the possible values for \(w\) are 0 and 1.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Sum of Numbers
Random variables are a way to quantify the outcomes of an experiment. When we talk about the "sum of numbers" in this particular exercise, we're looking at the result of adding together two selected numbers. Imagine picking two slips from the box without looking and adding them up. Consider the pairs of slips: (1,2), (1,3), (1,4), (2,3), (2,4), and (3,4). By adding these numbers together you get possible sums:
  • (1,2) gives 3
  • (1,3) gives 4
  • (1,4) results in 5
  • (2,3) also results in 5
  • (2,4) gives 6
  • (3,4) results in 7
Each sum is a potential value that the random variable can take. Always remember, in mathematics, the order in which you add numbers does not affect the final result.
Difference Calculation
Understanding difference calculations involves looking at how numbers vary. In this exercise, "difference" goes beyond subtraction. It's about knowing which number comes first. For example, selecting slips in the order (2,1) differs from choosing (1,2). When calculating differences:
  • (1,2) gives -1
  • (2,1) gives 1
  • Similarly (2,3) results in -1, and (3,2) results in 1
The numbers you choose dictate whether you should subtract one from the other, positively or negatively. Negative results show when the first number is smaller than the second. Zero appears when both are equal. So, the range of difference is from -3 to 3.
Selection of Even Numbers
Even numbers are those divisible by two. In our box of slips, we know numbers 2 and 4 are even. "Selection of even numbers" here means how many even numbers are picked as part of your two-slip draw. Consider all possible combinations of chosen slips:
  • A combination without any even numbers, like (1,3), results in 0 evens.
  • Choosing (1,2) or (3,2) features one even number.
  • Picking (2,4) includes both available even numbers.
When only two slips are drawn and checked for evenness, the possibilities are either 0, 1, or 2 even numbers. This is a good example of counting outcomes in a small sample.
Statistical Analysis
Statistical analysis of a random experiment typically involves investigating the potential outcomes. This exercise can be analyzed by calculating probabilities and understanding distributions. For example, think of how often you might pull a slip with the number 4 from the box. Since only one of the slips has a 4, your probability in a single draw is simple. Yet, exploring further, such as determining probabilities for sums and differences mentioned earlier, builds a foundation for complex probability studies. Statistics help make more informed decisions based on observable data:
  • Calculates frequency of events happening
  • Provides expectation values for various sums or differences
  • Assists in making predictions based on random variables
Understanding this basic statistical analysis can lead to a more profound comprehension of probability and risk in larger datasets. It's the foundation of making sense out of seemingly random outcomes.

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Most popular questions from this chapter

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