Math Problem Statement

Suppose that the random variable X is equal to the number of hits obtained by a certain baseball player in his next 3 at-bats. If P(X = 1) = 0.2, P(X = 2) = 0.3, and P(X = 0) = 2P(X = 3), then the value of E(X) is equal to?

Solution

We are given the probability distribution of a random variable XX, which represents the number of hits a baseball player obtains in the next 3 at-bats. The probabilities are:

  • P(X=1)=0.2P(X = 1) = 0.2
  • P(X=2)=0.3P(X = 2) = 0.3
  • P(X=0)=2P(X=3)P(X = 0) = 2P(X = 3)

We are tasked with finding the expected value E(X)E(X).

Step-by-step solution:

  1. Express P(X=3)P(X = 3) using the relationship given: P(X=0)=2P(X=3)P(X = 0) = 2P(X = 3) Let P(X=3)=p3P(X = 3) = p_3. Then: P(X=0)=2p3P(X = 0) = 2p_3

  2. The sum of all probabilities must equal 1: P(X=0)+P(X=1)+P(X=2)+P(X=3)=1P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) = 1 Substituting the known probabilities: 2p3+0.2+0.3+p3=12p_3 + 0.2 + 0.3 + p_3 = 1 Simplifying: 3p3+0.5=13p_3 + 0.5 = 1 3p3=0.53p_3 = 0.5 p3=0.53=160.1667p_3 = \frac{0.5}{3} = \frac{1}{6} \approx 0.1667 Therefore, P(X=3)=16P(X = 3) = \frac{1}{6} and P(X=0)=2×16=26=13P(X = 0) = 2 \times \frac{1}{6} = \frac{2}{6} = \frac{1}{3}.

  3. Now we calculate E(X)E(X): The expected value E(X)E(X) is given by the formula: E(X)=0×P(X=0)+1×P(X=1)+2×P(X=2)+3×P(X=3)E(X) = 0 \times P(X = 0) + 1 \times P(X = 1) + 2 \times P(X = 2) + 3 \times P(X = 3) Substituting the values: E(X)=0×13+1×0.2+2×0.3+3×16E(X) = 0 \times \frac{1}{3} + 1 \times 0.2 + 2 \times 0.3 + 3 \times \frac{1}{6} Simplifying: E(X)=0+0.2+0.6+0.5=1.3E(X) = 0 + 0.2 + 0.6 + 0.5 = 1.3

Thus, the value of E(X)E(X) is 1.3\boxed{1.3}, which corresponds to option (c).

Would you like further clarification on any steps?

Related Questions:

  1. How would the expected value change if P(X=1)P(X = 1) were increased?
  2. Can the sum of probabilities ever exceed 1?
  3. What is the variance for this probability distribution?
  4. How does the relationship between P(X=0)P(X = 0) and P(X=3)P(X = 3) affect the solution?
  5. What would the expected value be if XX followed a uniform distribution?

Tip:

Always remember that the sum of all probabilities in a probability distribution must equal 1, which is useful when solving for unknown probabilities.

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Math Problem Analysis

Mathematical Concepts

Probability
Expected Value
Random Variables

Formulas

E(X) = Σ [x * P(X = x)]
Sum of probabilities: P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) = 1

Theorems

Law of Total Probability

Suitable Grade Level

Grades 11-12