How Do Standard Deviations Affect Probability in Statistics Problems?

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SUMMARY

The discussion focuses on calculating probabilities related to standard deviations in statistics, specifically using a mean of 5.80 and a standard deviation of 0.64. For the first question, it is established that the probability of selecting a number over 2 standard deviations from the mean is 0%, as this exceeds the maximum value of 7. The second question addresses the probability of the sample mean exceeding 2 standard deviations, which requires understanding the standard deviation of the sample mean, calculated as 0.64 divided by the square root of the sample size (30).

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  • Understanding of basic statistics concepts, including mean and standard deviation.
  • Knowledge of the Central Limit Theorem and its implications for sample means.
  • Familiarity with probability distributions, particularly normal distribution.
  • Ability to perform calculations involving standard deviations and sample sizes.
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  • Learn how to calculate the standard deviation of the sample mean using the formula σ/√n.
  • Study the Central Limit Theorem and its significance in statistics.
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  • Practice problems involving standard deviations and probabilities in various statistical contexts.
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Students studying statistics, data analysts, and anyone involved in probability calculations or statistical analysis will benefit from this discussion.

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Homework Statement



My mean is 5.80
My standard deviation is 0.64
The largest number does not exceed 7

1) What is the probability the probability of randomly selecting a number, and the number being over 2 σ from the mean.

2) For a sample of 30, what is the probability the mean will be over 2 SD from the mean? 2. The attempt at a solution

1) It must be 0%, correct? As 2 sd greater than the mean exceeds all values there are?

2) This is the one that puzzles me. I genuinely do not understand why 30 samples do not have to be taken. Perhaps, it also has something to do with 2 σ from the mean exceeding all values?
 
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939 said:

Homework Statement



My mean is 5.80
My standard deviation is 0.64
The largest number does not exceed 7

1) What is the probability the probability of randomly selecting a number, and the number being over 2 σ from the mean.

2) For a sample of 30, what is the probability the mean will be over 2 SD from the mean? 2. The attempt at a solution

1) It must be 0%, correct? As 2 sd greater than the mean exceeds all values there are?

2) This is the one that puzzles me. I genuinely do not understand why 30 samples do not have to be taken. Perhaps, it also has something to do with 2 σ from the mean exceeding all values?

You are correct about question 1). While a laywer could argue that the question 2) is ambiguous, I would think the meaning is clear enough: the σ in question 2) refers to the standard deviation of the sample mean, not the standard deviation of the underlying random variable. In other words, you need a σ that is different from 0.64; do you know what the correct value should be?

RGV
 
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