Найдите математическое ожидание и лисперсию Найдите математическое ожидание для СВ Y, Z, W и дисперсию Y, Z, если известно: 1) M(X) = 6, D(X) = 4, где Y = X + 3, Z = 3X — 5,W = x² ; 2) M(X) = 8, D(X) = 0, где Y = 2X - 3, Z = X + 5, W = x² +3; 3) M(X) = 5, D(X) = 1, где Y = 3X + 4, Z = 2X — 6, W = (x-1)² ; 4) M(X) = 4, D(X) = 2, где Y = 6X + 2, Z = X + 5, W = x² - x 5) M(X) = 7, D(X) = 3, где Y = 2X + 7, Z = X — 5, W = x² − 2; 6) M(X) = 3, D(X) = 2, где Y = 5X — 3, Z = X + 5, W = x² − 3.
1) Для первого случая:
M(Y) = M(X) + 3 = 6 + 3 = 9
D(Y) = D(X) = 4
M(Z) = 3M(X) - 5 = 36 - 5 = 13
D(Z) = 9D(X) = 94 = 36
M(W) = M(X²) = D(X) + M(X)² = 4 + 6² = 40
D(W) = E(X⁴) - [E(X²)]² = 4 + 36 = 40
2) Для второго случая:
M(Y) = 2M(X) - 3 = 28 - 3 = 13
D(Y) = 4D(X) = 40 = 0
M(Z) = M(X) + 5 = 8 + 5 = 13
D(Z) = D(X) = 0
M(W) = M(X²) + 3 = D(X) + M(X)² + 3 = 0 + 8² + 3 = 67
D(W) = E(X⁴) - [E(X²)]² = 0 + 0 = 0
3) Для третьего случая:
M(Y) = 3M(X) + 4 = 35 + 4 = 19
D(Y) = 9D(X) = 91 = 9
M(Z) = 2M(X) - 6 = 25 - 6 = 4
D(Z) = 4D(X) = 41 = 4
M(W) = M((X-1)²) = M(X² - 2X + 1) = D(X) + M(X)² - 2M(X) + 1 = 1 + 5² - 25 + 1 = 17
D(W) = E(X⁴) - [E(X²)]² = 1 + 4 = 5
4) Для четвертого случая:
M(Y) = 6M(X) + 2 = 64 + 2 = 26
D(Y) = 36D(X) = 362 = 72
M(Z) = M(X) + 5 = 4 + 5 = 9
D(Z) = D(X) = 2
M(W) = M(X² - X) = D(X) + M(X)² - M(X) = 2 + 4² - 4 = 12
D(W) = E(X⁴) - [E(X²)]² = 2 + 16 = 18
5) Для пятого случая:
M(Y) = 2M(X) + 7 = 27 + 7 = 21
D(Y) = 4D(X) = 43 = 12
M(Z) = M(X) - 5 = 7 - 5 = 2
D(Z) = D(X) = 3
M(W) = M(X² - 2) = D(X) + M(X)² - 2 = 3 + 7² - 2 = 48
D(W) = E(X⁴) - [E(X²)]² = 3 + 9 = 12
6) Для шестого случая:
M(Y) = 5M(X) - 3 = 53 - 3 = 12
D(Y) = 25D(X) = 252 = 50
M(Z) = M(X) + 5 = 3 + 5 = 8
D(Z) = D(X) = 2
M(W) = M(X² - 3) = D(X) + M(X)² - 3 = 2 + 3² - 3 = 5
D(W) = E(X⁴) - [E(X²)]² = 2 + 4 = 6