Math Problem Statement

let z be the standard normal variable. find the value of z if z satisfies P(-z<Z<z)=0.2468

Solution

To solve for zz in the probability statement P(z<Z<z)=0.2468P(-z < Z < z) = 0.2468, we need to understand that this represents the probability that a standard normal variable ZZ lies within the symmetric interval (z,z)(-z, z) about the mean 0 of the standard normal distribution.

Steps:

  1. Symmetry of the Standard Normal Distribution: Since the standard normal distribution is symmetric, the probability P(z<Z<z)P(-z < Z < z) corresponds to the cumulative probability from z-z to zz, and the tails of the distribution (outside this interval) must sum up to the remaining probability.

  2. Relation to the Standard Normal Table: The total probability under the normal curve is 1. If P(z<Z<z)=0.2468P(-z < Z < z) = 0.2468, then the probability in the tails (outside the interval (z,z)(-z, z)) is: 10.2468=0.75321 - 0.2468 = 0.7532 Since the distribution is symmetric, the probability in each tail is: 0.75322=0.3766\frac{0.7532}{2} = 0.3766

  3. Using the Standard Normal Table: Now we look for the value of zz such that the cumulative probability from -\infty to zz is 0.37660.3766. This corresponds to the cumulative distribution function (CDF) for ZZ.

  4. Finding zz: Using a standard normal distribution table or calculator, we find the z-value that gives a cumulative probability of 0.3766.

The z-value that corresponds to a cumulative probability of 0.3766 is approximately z=0.314z = -0.314.

Thus, z0.314z \approx 0.314 (we consider the positive value since the interval is symmetric).

Final Answer:

The value of zz that satisfies P(z<Z<z)=0.2468P(-z < Z < z) = 0.2468 is approximately z=0.314z = 0.314.

Would you like further details on this, or do you have any additional questions?

Here are some related questions:

  1. What is the meaning of a standard normal distribution?
  2. How do you use the z-table to find probabilities?
  3. What is the relationship between probability and the cumulative distribution function (CDF)?
  4. How do you calculate probabilities for non-standard normal distributions?
  5. What is the significance of symmetric intervals in normal distribution problems?

Tip: When working with z-values and probabilities, always check whether the problem refers to a one-tailed or two-tailed scenario, as it affects the interpretation of the probability.

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Math Problem Analysis

Mathematical Concepts

Probability
Standard Normal Distribution
Symmetry in Normal Distribution

Formulas

P(-z < Z < z) = Probability of Z lying within the interval (-z, z)
Cumulative probability: P(Z < z)

Theorems

Standard Normal Distribution Theorem
Properties of Symmetry in Normal Distribution

Suitable Grade Level

Grades 10-12 (High School)