Question

x is a binomial random variable. (Give your answers correct to three decimal places.)
(a) Calculate the probability of x for: n = 1, x = 0, p = 0.15
P(x) = Correct: Your answer is correct. . (0.85)

(b) Calculate the probability of x for: n = 3, x = 3, p = 0.15
P(x) = Incorrect: Your answer is incorrect. . (0.68)

(c) Calculate the probability of x for: n = 5, x = 0, p = 0.8
P(x) = Correct: Your answer is correct. . (0.00)

(d) Calculate the probability of x for: n = 1, x = 1, p = 0.4
P(x) = Correct: Your answer is correct. . (0.40)

(e) Calculate the probability of x for: n = 3, x = 1, p = 0.45
P(x) = Incorrect: Your answer is incorrect. . (0.45)

(f) Calculate the probability of x for: n = 6, x = 6, p = 0.25
P(x) = (1.50)
I worked these all the same way got three right and three wrong can someone explain to me how???? I multiplied p to x to get answers.

Answer 1

What did you do for #a?

P(n=1, x=0, p=0.15)
=nPx 0.15^0((1-0.15)^(1-0)
=1!/(0!1!)(0.15^0)(0.85)^1
=1*1*0.85
=0.85

For #b,
P(n=3,x=3,p=0.15)
=3P3 (0.15^3)(1-0.15)^(3-3)
=1*(0.003375)(0.85^0)
=0.003375

Check out the other numbers using
P(n,x,p)
=nPx (p^x)(q^(n-x))
where q=(1-p)