Math Problem Statement

An unfair die looks like an ordinary six-sided die, but the outcomes are not equally likely. Given a probability distribution, calculate P(4 ≤ X ≤ 5), P(2 ≤ X < 4), and P(X ≤ 5).

Solution

Let's solve the given problem based on the probability distribution table you provided:

xP(x)
00
10.12
20.20
30.34
40.17
50.13
60.04

We need to compute the following probabilities:


a. P(4X5)P(4 \leq X \leq 5)

This asks for the probability that XX is between 4 and 5, inclusive.
P(4X5)=P(X=4)+P(X=5)P(4 \leq X \leq 5) = P(X = 4) + P(X = 5) P(4X5)=0.17+0.13=0.30P(4 \leq X \leq 5) = 0.17 + 0.13 = 0.30

Answer: 0.30


b. P(2X<4)P(2 \leq X < 4)

This asks for the probability that XX is between 2 and 4, where 2 is included, but 4 is not.
P(2X<4)=P(X=2)+P(X=3)P(2 \leq X < 4) = P(X = 2) + P(X = 3) P(2X<4)=0.20+0.34=0.54P(2 \leq X < 4) = 0.20 + 0.34 = 0.54

Answer: 0.54


c. P(X5)P(X \leq 5)

This asks for the cumulative probability that XX takes any value from 0 to 5, inclusive.
P(X5)=P(X=0)+P(X=1)+P(X=2)+P(X=3)+P(X=4)+P(X=5)P(X \leq 5) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) + P(X = 5) P(X5)=0+0.12+0.20+0.34+0.17+0.13=0.96P(X \leq 5) = 0 + 0.12 + 0.20 + 0.34 + 0.17 + 0.13 = 0.96

Answer: 0.96


If anything is unclear or you'd like more detailed steps, feel free to ask!


5 Related Questions:

  1. What is the total probability sum for any valid probability distribution?
  2. How would the probabilities change if the die was fair (uniform distribution)?
  3. How do you calculate P(3<X6)P(3 < X \leq 6) using this table?
  4. Can we treat this die as biased, and how does that affect expected value calculations?
  5. What is the expected value E(X)E(X) for this distribution?

Tip: Always make sure the sum of all probabilities in a distribution equals 1 to confirm it’s valid.

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Math Problem Analysis

Mathematical Concepts

Probability Distribution
Discrete Random Variables

Formulas

P(4 ≤ X ≤ 5) = P(X = 4) + P(X = 5)
P(2 ≤ X < 4) = P(X = 2) + P(X = 3)
P(X ≤ 5) = Σ P(X = i) for i = 0 to 5

Theorems

Basic Probability Theorem

Suitable Grade Level

Grades 9-12