If variance of x is 5, then find the variance of (2 – 3x)(a) 10(b) 45(c) 5(d) -13
Question
If variance of x is 5, then find the variance of (2 – 3x)(a) 10(b) 45(c) 5(d) -13
Solution
The variance of a random variable X is given by Var(X). If we have a new variable Y = aX + b, where a and b are constants, then the variance of Y is given by Var(Y) = a^2 * Var(X).
In this case, X has a variance of 5, and we want to find the variance of Y = 2 - 3X.
Step 1: Identify the constants a and b in the equation Y = aX + b. Here, a = -3 (the coefficient of X) and b = 2 (the constant term).
Step 2: Substitute the values of a and Var(X) into the formula Var(Y) = a^2 * Var(X).
Var(Y) = (-3)^2 * 5 = 9 * 5 = 45.
So, the variance of Y = 2 - 3X is 45. Therefore, the correct answer is (b) 45.
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