If the random variable X has mean 3 and standard deviation 5, then what is the variance of the random variable Y = 2X - 5 ?

Explanation

If Y = aX + b, then Var(Y) = a^2 Var(X). Given the standard deviation of X is 5, Var(X) = 25. Thus, Var(Y) = 2^2 * 25 = 100.

Related questions on Statistics & Probability

• Let x be the mean of squares of first n natural numbers and y be the square of mean of first n natural numbers. If $\frac{x}{y}=\fra...
• What is the probability of getting a composite number in the list of natural numbers from 1 to 50?
• Two numbers x and y are chosen at random from a set of first 10 natural numbers. What is the probability that (x+y) is divisible by 4?
• A number x is chosen at random from first n natural numbers. What is the probability that the number chosen satisfies $x+\frac{1}{x} \gt...
• Three fair dice are tossed once. What is the probability that they show different numbers that are in AP?