Finding the Probability of a Random Event Probability

Probability 2 Comments

Part of the reason some people have trouble with probability questions is that it’s not always clear which technique to use to solve a problem. This particular how-to will guide you through solving problems that give a percentage (e.g. 76% of Americans are in favor of Universal Health Care), then ask you to calculate the probability of picking a certain number (e.g. 3 people) and having them all fall into a particular group (in our case, they are in favor of health care).

Step 1: Change the given percentage to a decimal. In our example:
76% = 0.76

Step 2:. Multiply the decimal found it step 1 by itself. Repeat for as many times as you are asked to choose an item. For example, if you were to pick 3 items at random, multiply 0.76 by itself 3 times:

0.76 x 0.76 x 0.76 = .4389 (rounded to 4 decimal places)

That’s it!

Related posts:

  1. How to find the probability of an event NOT happening
  2. How to find the probability of a simple event happening
  3. How to find the Probability of an Event, Given Another Event
  4. How to Find the Probability of Two Events Occuring Together
  5. Normal Distribution Word Problems: Finding upper and lower cut off points
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2 Responses to “Finding the Probability of a Random Event Probability”

  1. How to Do Everything Statistics » How to find the probability of a simple event happening said:

    Sep 14, 09 at 7:05 am

    [...] tell you how to find the probability of a simple event happening. Other articles on this topic: How to find the probability of picking a certain number of items given a percentage Finding the probability of an event not happening Finding probabilities using frequency [...]

  2. Lisa Barcomb said:

    Sep 25, 09 at 8:46 am

    Wow I know I had these kinds of problems already but I didn’t understand it until now the light came on in my head. I wish they were all like this 1, 2 and then you are done. I like these that are short and sweet. Its just amazing how sometimes you have to do things over several times before it clicks in your head or at least thats how it works for me.

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