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Binomial Distribution Question

"The probability that a seed of the Staghill daisy will grow 0.6.

What is the least number of seeds that must be planted so that the probability that at least 5 grow is greater that 90%. Fully justify your answer."

Can anyone help me on where to start? How do I approach this question?
Original post by alwaysneedadvice
"The probability that a seed of the Staghill daisy will grow 0.6.

What is the least number of seeds that must be planted so that the probability that at least 5 grow is greater that 90%. Fully justify your answer."

Can anyone help me on where to start? How do I approach this question?

If X is the number of seeds that grows, then we can write down that X~B(n, 0.6), where n is unknown. We require that P(X >= 5) >= 0.9. I would suggest that you turn that into a "<=" statement and play around with a few trial values of n. You could justify your answer fully by listing the probabilities for three consecutive values of n, with the right one in the middle of the list.
Original post by old_engineer
If X is the number of seeds that grows, then we can write down that X~B(n, 0.6), where n is unknown. We require that P(X >= 5) >= 0.9. I would suggest that you turn that into a "<=" statement and play around with a few trial values of n. You could justify your answer fully by listing the probabilities for three consecutive values of n, with the right one in the middle of the list.

Ok thanks, is there not a way of doing it using the binomial distribution formula?
Original post by alwaysneedadvice
Ok thanks, is there not a way of doing it using the binomial distribution formula?

Not as far as I know.

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