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Binomial distribution help!

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    I struggle how to find a value once it can't be gained from using the table. hard to explain so ill have to use a question.

    The probability of producing a read flower is 0.6. A gardener plants 20 of these bulbs.

    Find the probability that the number of read flowers produces is at least 12.

    I know you have B(20, 0.6) then B(20,0.4)

    at least 12 = (x greater than equal to 12) but looking at the answer/ mark scheme they've used (x less than or equal to 8). How do you get this?
  2. Offline

    Hi mate, hard to explain this one on here but I'll give it a shot.

    You've sussed the hardest part of it:

    If X - B(20,0.6) then 'X - B(20,0.4)

    So we are looking for the Probability that X>=12. Just think about it. If X is going to be 12,13,14.....20. Then 'X has to be 8,7,6........0

    So the probability of X>=12 is equal to the probability of 'X<=8.

    Now we can use the table.


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