POISSON(x,mean,cumulative)
=POISSON(3,2.5,FALSE)
For example, if you wanted to calculate the probability of three successes when the mean number of successes is 2.5, you would use the POISSON function as above. This would return 0.19358.
=POISSON(2,2,TRUE)
If you wanted to calculate the cumulative Poisson probability for two successes when the mean number of successes is 2, you would use the POISSON function, such as above. This would return 0.67667.
=POISSON(5,4,FALSE)
For example, if you wanted to calculate the probability of five successes when the mean number of successes is 4, you would use the POISSON function, such as above. This would return 0.17603.
=POISSON(3,5,TRUE)
If you wanted to calculate the cumulative Poisson probability for three successes when the mean number of successes is 5, you would use the POISSON function such as above. This would return 0.72212.
The POISSON function has been replaced by new functions with better accuracy that better reflect their usage. These new functions can be used to predict the number of events over a specific time period.