binomial probability (1 Viewer)

[ToO LaZy ^*]

what does it mean when you are asked to find the probability of something occuring AT LEAST X times...??

eg.
a coin is tossed 10 times. find the probability of tossing
i) at least 9 tails

 

[Estel]

"a coin is tossed 10 times. find the probability of tossing
i) at least 9 tails"

means 9 or 10
so the answer is
10C9(1/2)^10 + 10C10(1/2)^10

 

[ToO LaZy ^*]

ohhhhhhhhhhhhhhhhhhhhhhh...i get it...
cheers

 

[Teoh]

'at least' generally means a sum of probabilities...i think?