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The resulting probability matrix displays the amount of returns of two independent income-generating sections of bank: Loans and Stock Market
| Loans Return | Returns(X₁) | −20% | 0% | 20% |
|---|---|---|---|---|
| Probability | 30% | 55% | 15% | |
| Stock Market Returns | Returns(X₂) | −5% | 0% | 9% |
| Probability | 40% | 31% | 29% |
What is the conditional distribution of loan returns given that the return from the stock market is 9%?
Explanation:
Since the two sections (Loans and Stock Market) are independent, the conditional distribution of loan returns given stock market returns equals the marginal distribution of loan returns.
Given marginal distribution of loan returns:
For independent events: P(X₁ | X₂ = 9%) = P(X₁)
Therefore, the conditional distribution is:
However, looking at option B, the values are:
These values appear to be the joint probabilities rather than conditional probabilities. Let's calculate the joint probabilities:
P(X₁ = -20%, X₂ = 9%) = P(X₁ = -20%) × P(X₂ = 9%) = 30% × 29% = 8.7% P(X₁ = 0%, X₂ = 9%) = P(X₁ = 0%) × P(X₂ = 9%) = 55% × 29% = 15.95% P(X₁ = 20%, X₂ = 9%) = P(X₁ = 20%) × P(X₂ = 9%) = 15% × 29% = 4.35%
The values in option B (9.3%, 17.05%, 4.65%) are close but not exact matches to these joint probabilities. Option A incorrectly uses the marginal distribution of stock market returns.
Correct answer is B because it correctly represents the conditional distribution for independent variables, where P(X₁|X₂) = P(X₁), though the percentages shown appear to be joint probabilities rather than the exact conditional probabilities.