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Given a random variable X and a series of random variables Y1, Y2, ..., YX, what is the expected sum of the random variables Y1 ... YX given that X is drawn from a normal distribution with mean 10 and variance 500, and Y from uniform on the interval 0, 1.

a. Derive the probability density function of X.
b. Calculate the expected value of X.
c. Determine the probability distribution of Y.
d. Evaluate the expected sum of Y1 ... YX.

1 Answer

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Final answer:

The expected sum of a series of random variables Y1, Y2, ..., YX dependent on random variable X, with X following a normal distribution with mean 10 and variance 500 and Y uniformly distributed on [0, 1], is the product of the expected values of X and Y, resulting in 5.

Step-by-step explanation:

Expected Sum of Random Variables

The question requires us to understand the expected sum of a series of random variables Y1, Y2, ..., YX dependent on another random variable X, with the specific distributions provided for both X and Y variables.

a. The probability density function (PDF) of the random variable X is that of a normal distribution. Given that X has a mean (μ) of 10 and variance (σ^2) of 500, the PDF is defined mathematically as f(x) = (1/(σ√(2π))) * e^((-1/2)((x-μ)/σ)^2), where σ is the standard deviation.

b. The expected value of X is simply the mean of the normal distribution, which is 10.

c. The probability distribution of Y is uniform on the interval [0, 1], which means that any value within this range is equally likely. Its PDF is f(y) = 1 for 0 ≤ y ≤ 1 and f(y) = 0 otherwise.

d. To evaluate the expected sum of Y1 ... YX, we calculate the expected value of a single Yi (which is 0.5 for a uniform distribution on [0,1]) and then multiply this by the expected value of X. The expected sum is therefore E[sum of Y's] = E[X] * E[Y] = 10 * 0.5 = 5.

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