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The random variable x represents the number of emails a student receives on a day. Assume it has a Poisson distribution with a mean of 6 emails. Find each probability below. Round your answer to four decimal places.

A) P(x is exactly 2)
B) P(x is at least 2)
C) P(x is less than 2)
D) P(x is at most 2)
E) P(x is more than 2)

User Treehouse
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Final answer:

The probabilities associated with the Poisson distribution where the mean number of emails is 6 can be calculated using the Poisson probability mass function and cumulative distribution functions, with final answers rounded to four decimal places.

Step-by-step explanation:

The random variable x represents the number of emails a student receives on a day. Given that it follows a Poisson distribution with a mean of 6 emails (X ~ P(6)), we can calculate the various probabilities requested:

  • A) The probability that x is exactly 2: P(x = 2) is calculated using the Poisson probability mass function (PMF). For a Poisson distribution with a mean (λ) of 6, PMF is given by P(x; λ) = (e-λ * λx) / x!, where e is the base of the natural logarithm. Thus P(x = 2; 6) = (e-6 * 62)/2!.
  • B) The probability that x is at least 2: P(x ≥ 2) = 1 - P(x < 2) which is 1 minus the cumulative distribution for x = 0 and x = 1.
  • C) The probability that x is less than 2: P(x < 2) = P(x = 0) + P(x = 1).
  • D) The probability that x is at most 2: P(x ≤ 2) = P(x < 2) + P(x = 2) since it includes 2.
  • E) The probability that x is more than 2: P(x > 2) = 1 - P(x ≤ 2).

For A, B, C, and D, one would typically use the Poisson PMF and cumulative distribution functions, possibly through a calculator or software that has these statistical functions built-in. Rounding to four decimal places as specified would provide the final probabilities.

User Avagdar
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