The Student Room Group

Probability maths question

A fair dice is rolled twenty times. The event A is defined as follows: A occurs if and only if
three or more of the rolls result in a six. Evaluate P(A), and give your answer to three decimal
places
How would i answer this question?
Original post by SaraGirl
A fair dice is rolled twenty times. The event A is defined as follows: A occurs if and only if
three or more of the rolls result in a six. Evaluate P(A), and give your answer to three decimal
places
How would i answer this question?

the number of sixes follows a Binomial distribution, with n = 20 and p = 1/6
Original post by SaraGirl
A fair dice is rolled twenty times. The event A is defined as follows: A occurs if and only if
three or more of the rolls result in a six. Evaluate P(A), and give your answer to three decimal
places
How would i answer this question?

What have you tried?
Reply 3
(Original post by the bear)the number of sixes follows a Binomial distribution, with n = 20 and p = 1/6


Thank you, but when doing P(X = r), what is the value of r in this case?
Reply 4
Original post by Muttley79
What have you tried?

I understand what the person above you said, but im just trying to put all the numbers into the formula for figuring out the probability. Im confused because its 3 or more successes, not just 3 successes
Original post by SaraGirl
I understand what the person above you said, but im just trying to put all the numbers into the formula for figuring out the probability. Im confused because its 3 or more successes, not just 3 successes

To get 3 or more successes you can do 1 - [ p(0 successes) + p(1 success) + p(2 successes) ]
Reply 6
Original post by Quadrinomial
To get 3 or more successes you can do 1 - [ p(0 successes) + p(1 success) + p(2 successes) ]

Thank you so much, that makes sense

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