# X is a random variable with the distribution B(12,0.42)?

How to calculate c? The answer for C is 0.81%

The answers for a and b are 0.1853 and 0.1838Thanks

### 1 Answer

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- fcas80Lv 72 months ago
a. P(X = x) = (nCx) * (p^x) * (1-p)^(n-x) = (12Cx) * (0.42^x) * (1-0.42)^(12-x)

P(X = 0) = 0.0014

P(X = 1) = 0.0126

P (X = 2) = 0.0502

P (X = 3) = 0.1211

P(X < 4) =.1853

b. P(X < 4) = P(X < 3.5) = P(Z < (3.5 - 12*.42)/SQRT(12*.42*.58)) = P(Z < -.9007) = .1839

c. 1 - .1853/.1839 = -.0076, or -0.76%

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