CIE A Level Maths: Probability & Statistics 1复习笔记3.2.2 Calculating Binomial Probabilities
Calculating Binomial Probabilities
Where does the formula for a binomial distribution come from?
The formula allows statisticians to quickly find probabilities for larger values of n without needing to draw the whole tree diagram- Your calculator may have a function that would allow you to calculate binomial probabilities
- You can learn how to use this to check your work but it is important you always show your working using the formula to get the marks in the exam
How do I calculate the cumulative probabilities for a binomial distribution?
- Most of the time you will be required to calculate cumulative binomial probabilities rather than individual ones
- Use the formula to find the individual probabilities and then add them up
- Make sure you are confident working with inequalities for discrete values
- Only integer values will be included so it is easiest to look at which integer values you should include within your calculation
- Sometimes it is quicker to find the probabilities that are not being asked for and subtract from one
Worked Example
Exam Tip
- Looking carefully at the inequality within the probability is key here, make sure you consider which integers should be counted within your calculations.
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