Math check and question
posted by Nora 57 on .
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.

What did you do for #a?
P(n=1, x=0, p=0.15)
=nPx 0.15^0((10.15)^(10)
=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)(10.15)^(33)
=1*(0.003375)(0.85^0)
=0.003375
Check out the other numbers using
P(n,x,p)
=nPx (p^x)(q^(nx))
where q=(1p)