Question

If X foolows N(10,1) and U =120 +6X, then variance of U is,

Answer 1

Answer:

Step-by-step explanation:

Given:  mean = 10; variance = 1      (since N(10,1)

Find: var(U)

       U = 120 + 6X

var(U) = var(120) + var(6X)

           = 0 + (6)^2 * var(X)         (since var. of constant is zero)

           = 36 *1

           = 36

Note:

    Multiplying a r.v by a constant increases the var. by the sqr. of the constant. [var(6X) = 6^2 * var(X).