Assume the random variable X has a binomial

ngeipk8

ngeipk8

Answered question

2022-08-25

Assume the random variable X has a binomial distribution with the given probability of obtaining a success. Find the following probability, given the number of trials and the probability of obtaining a success. Round your answer to four decimal places.

P(X>2)P(X>2), n=6n=6, p=0.7p=0.7

Answer

Answer & Explanation

Eliza Beth13

Eliza Beth13

Skilled2023-05-31Added 130 answers

To solve the problem, we are given the random variable X, which has a binomial distribution with parameters n and p. Here, n represents the number of trials, and p represents the probability of obtaining a success in each trial. We need to find the probability P(X > 2) when n = 6 and p = 0.7.
The probability mass function (PMF) of a binomial distribution is given by the formula:
P(X=k)=(nk)·pk·(1p)nk
where (nk) represents the binomial coefficient, which is the number of ways to choose k successes out of n trials.
To find P(X > 2), we need to calculate the probability of X being greater than 2, which includes the probabilities of X being 3, 4, 5, and 6. We can calculate each probability separately and then sum them up.
P(X>2)=P(X=3)+P(X=4)+P(X=5)+P(X=6)
Let's calculate each term step by step:
P(X=3)=(63)·(0.7)3·(10.7)63
P(X=3)=(63)·(0.7)3·(0.3)3
To calculate the binomial coefficient (63), we use the formula:
(63)=6!3!·(63)!
(63)=6!3!·3!=6·5·43·2·1=20
Substituting the values into the formula, we have:
P(X=3)=20·(0.7)3·(0.3)3
Calculating this expression gives:
P(X=3)0.3087
Next, we calculate the probability for X = 4:
P(X=4)=(64)·(0.7)4·(10.7)64
P(X=4)=(64)·(0.7)4·(0.3)2
Using the binomial coefficient formula, we find:
(64)=6!4!·(64)!=6·52·1=15
Substituting the values into the formula, we have:
P(X=4)=15·(0.7)4·(0.3)2
Calculating this expression gives:
P(X=4)0.1852
Next, we calculate the probability for X = 5:
P(X=5)=(65)·(0.7)5·(10.7)65
P(X=5)=(65)·(0.7)5·(0.3)1
Using the binomial coefficient formula, we find:
(65)=6!5!·(65)!=61=6
Substituting the values into the formula, we have:
P(X=5)=6·(0.7)5·(0.3)1
Calculating this expression gives:
P(X=5)0.0882
Finally, we calculate the probability for X = 6:
P(X=6)=(66)·(0.7)6·(10.7)66
P(X=6)=(66)·(0.7)6·(0.3)0
Using the binomial coefficient formula, we find:
(66)=6!6!·(66)!=11=1
Substituting the values into the formula, we have:
P(X=6)=1·(0.7)6·(0.3)0
Calculating this expression gives:
P(X=6)0.1176
Now, we can find the probability P(X > 2) by summing up the probabilities we calculated:
P(X>2)=P(X=3)+P(X=4)+P(X=5)+P(X=6)
P(X>2)0.3087+0.1852+0.0882+0.1176
Calculating this expression gives:
P(X>2)0.6997
Therefore, the probability of X being greater than 2, given n = 6 and p = 0.7, is approximately 0.6997. Rounded to four decimal places, the answer is 0.6997.

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