A binomial distribution has a probability of success = 0.4
Calculate the probability of exactly 3 successes in 10 trials:
f(k;n,p) = | n! * pkqn - k | |
k!(n - k)! |
q = 1 - p
q = 1 - 0.4
q = 0.6
n! = 10!
10! = 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1
10! = 3628800
k! = 3!
3! = 3 * 2 * 1
3! = 6
(n - k)! = (10 - 3)!
(n - k)! = 7!
7! = 7 * 6 * 5 * 4 * 3 * 2 * 1
7! = 5040
P(X = 3) = | 10! * 0.430.6(10 - 3) | |
3!(10 - 3)! |
P(X = 3) = | 3628800 * 0.064 * 0.67 | |
6 * 5040 |
P(X = 3) = | 3628800 * 0.064 * 0.0279936 | |
30240 |
P(X = 3) = | 6501.32324352 | |
30240 |
Since q = 1 - p, we have n(1 - p) = 10(1 - 0.4)
nq = 10(0.6)
nq = 6
μ = np
μ = 10 x 0.4
μ = 4
σ2 = np(1 - p)
σ2 = 10 x 0.4 x (1 - 0.4)
σ2 = 4 x 0.6
σ2 = 2.4
σ = √σ2 = √np(1 - p)
σ = √2.4
σ = 1.5492
Skewness = | 1 - 2p |
√np(1 - p) |
Skewness = | 1 - 2(0.4) |
√10(0.4)(1 - 0.4) |
Skewness = | 1 - 0.8) |
√10(0.4)(0.6) |
Skewness = | 0.2 |
√2.4 |
Skewness = 0.083333333333333
Kurtosis = | 1 - 6p(1 - p) |
np(1 - p) |
Kurtosis = | 1 - 6(0.4)(1 - 0.4) |
10(0.4)(1 - 0.4) |
Kurtosis = | 1 - (2.4)(0.6) |
10(0.4)(0.6) |
Kurtosis = | 1 - 1.44 |
2.4 |
Kurtosis = -0.18333333333333