Probability Help: Formulas for Random Variables with Mean 5 and Variance 12

  • Thread starter xhallie
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In summary, the conversation is about a person asking for guidance on dealing with random variables, specifically in the context of a refresher worksheet for a probability class. The person provides information about a specific scenario involving a random variable with a given mean and variance, and asks for the expected value, variance, and normal distribution of a related variable. They also express gratitude for any help provided.
  • #1
xhallie
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So I took probability last year, and for one of my classes we have an optional refresher worksheet, but I cannot remember how to deal with random variables :(

I don't need the answer -- just some guidance on what formulas to use please!

x is a random variable with mean 5 and variance 12.

y = 3 + 9x

a) what is the expected valued of y?

b) what is the variance and SD of y?

c) is y normally distributed?

thank you so much!
 
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  • #2
Welcome to PF, xhallie! :smile:

Here's a page I just googled, which I believe answers your questions:
http://www.kaspercpa.com/statisticalreview.htm
 

1. What is probability?

Probability is a mathematical concept that measures the likelihood of an event occurring. It is represented by a number between 0 and 1, where 0 indicates impossibility and 1 indicates certainty.

2. How is probability calculated?

Probability is calculated by dividing the number of favorable outcomes by the total number of possible outcomes. This can be expressed as a fraction, decimal, or percentage.

3. What is the difference between theoretical probability and experimental probability?

Theoretical probability is based on mathematical calculations and assumes that all outcomes are equally likely. Experimental probability is based on actual data collected from experiments or observations and may differ from theoretical probability due to chance or external factors.

4. How can probability be used in real life?

Probability is used in various fields such as statistics, economics, and science to make predictions and informed decisions. It can help in risk assessment, weather forecasting, and even in everyday activities like playing games or making financial investments.

5. Can probability be manipulated?

No, probability cannot be manipulated. It is a mathematical concept that is based on objective calculations and cannot be influenced by external factors. However, the interpretation of probability can be subjective and may vary depending on the context.

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