Question 1176779
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Hi
Normal distribution:  mean of 3, a variance of 9  and σ = 3
Sample:  n = 50
  {{{z =blue (x - mu)/blue(sigma/sqrt(n))}}}  3/sqrt(50) = .4242640687

 P( x̄ > 4) = 1 - P( x̄ ≤  4)  0r 1 - P(z ≤ 1/(3/sqrt(50)) = 1-.6306

 P( x̄ < 2.5) = P( x̄ ≤ 2.5)  0r P(z ≤ -.5/(3/sqrt(50)) = .4338

 P( x̄ < .5) = P( x̄ ≤ .5)  0r P(z ≤ -2.5/(3/sqrt(50)) = .2023

Wish You the Best in your Studies.
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