Math Problem Statement

Suppose Z follows the standard normal distribution. Use the calculator provided, or this table, to determine the value of c so that the following is true. P(-1.24 ≤ Z≤ c)=0.8746 Carry your intermediate computations to at least four decimal places. Round your answer to two decimal places.

Solution

To solve the problem, we are given that ZZ follows the standard normal distribution, and we are asked to find the value of cc such that:

P(1.24Zc)=0.8746P(-1.24 \leq Z \leq c) = 0.8746

Step 1: Find P(Z1.24)P(Z \leq -1.24)

Using a standard normal distribution table or a calculator, we first find the probability for Z=1.24Z = -1.24. From the standard normal table:

P(Z1.24)=0.1075P(Z \leq -1.24) = 0.1075

Step 2: Set up the equation

We are told that the probability between Z=1.24Z = -1.24 and Z=cZ = c is 0.8746. This can be written as:

P(1.24Zc)=P(Zc)P(Z1.24)P(-1.24 \leq Z \leq c) = P(Z \leq c) - P(Z \leq -1.24)

Substitute the known probability for Z1.24Z \leq -1.24:

0.8746=P(Zc)0.10750.8746 = P(Z \leq c) - 0.1075

Step 3: Solve for P(Zc)P(Z \leq c)

Add 0.1075 to both sides:

P(Zc)=0.8746+0.1075=0.9821P(Z \leq c) = 0.8746 + 0.1075 = 0.9821

Step 4: Find cc

Now, we look up the value of cc such that P(Zc)=0.9821P(Z \leq c) = 0.9821 using the standard normal distribution table or a calculator.

From the table, Z=2.08Z = 2.08 corresponds to P(Z2.08)=0.9821P(Z \leq 2.08) = 0.9821.

Thus, c=2.08c = 2.08.

Final Answer:

The value of cc is approximately 2.08.


Would you like more details or have any questions? Here are some related questions you might find helpful:

  1. How do you use the standard normal table to find probabilities?
  2. What is the relationship between cumulative probability and the Z-score?
  3. How does changing the limits of integration affect the cumulative probability in a normal distribution?
  4. What is the significance of the value of cc in this problem?
  5. How do you calculate probabilities for non-standard normal distributions?

Tip: When working with the standard normal distribution, always confirm whether you are working with left-tailed or right-tailed probabilities to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Probability
Standard Normal Distribution
Cumulative Probability

Formulas

P(-1.24 ≤ Z ≤ c) = P(Z ≤ c) - P(Z ≤ -1.24)
P(Z ≤ c) = 0.8746 + P(Z ≤ -1.24)

Theorems

Standard Normal Distribution Table
Z-Score Calculation

Suitable Grade Level

Undergraduate/Advanced High School