Math Problem Statement

Stoaches are fictional creatures that feed on funistrada.

According to Wikipedia, adult stoach weights are normally distributed, with a mean of 452 g and a standard deviation of 61 g.

You weigh a random sample of 48 stoaches, and find a sample mean weight of 462.8 g.

Assume Wikipedia is correct about the standard deviation. What is the 𝑝 -value for a two-sided hypothesis test that Wikipedia is also right about the mean weight? (Give your answer to 4 decimal places.)

Solution

To find the pp-value for the two-sided hypothesis test, we'll follow these steps:

Step 1: State the hypotheses

  • Null hypothesis (H0H_0): The population mean weight of stoaches is 452 g.
  • Alternative hypothesis (H1H_1): The population mean weight of stoaches is not 452 g.

Step 2: Calculate the test statistic

The test statistic for the sample mean can be calculated using the following formula for the zz-score:

z=xˉμ0σnz = \frac{\bar{x} - \mu_0}{\frac{\sigma}{\sqrt{n}}}

where:

  • xˉ\bar{x} is the sample mean (462.8 g),
  • μ0\mu_0 is the hypothesized population mean (452 g),
  • σ\sigma is the population standard deviation (61 g),
  • nn is the sample size (48).

Plugging in the values:

z=462.84526148z = \frac{462.8 - 452}{\frac{61}{\sqrt{48}}}

Step 3: Calculate the z-value

We can now calculate this z-value.

z=10.86148z = \frac{10.8}{\frac{61}{\sqrt{48}}}

Let's calculate it.The calculated zz-value is approximately 1.22661.2266.

Step 4: Calculate the pp-value

For a two-sided test, the pp-value is calculated as:

p=2×P(Z>z)p = 2 \times P(Z > |z|)

We'll now find the pp-value using the standard normal distribution table or by calculating it directly.The pp-value for the two-sided hypothesis test is approximately 0.22000.2200.

Summary

Given a pp-value of 0.2200, there is not enough evidence to reject the null hypothesis at common significance levels (e.g., 0.05). This suggests that the sample mean does not provide strong evidence against the hypothesis that the population mean is 452 g.

Do you want further details or have any questions?

Here are 5 related questions:

  1. How would the pp-value change if the sample size increased?
  2. What is the relationship between the pp-value and the significance level in hypothesis testing?
  3. How do we interpret a pp-value in the context of hypothesis testing?
  4. What would the pp-value be if the sample mean were 455 g instead?
  5. How does the standard deviation affect the zz-score in this test?

Tip: When interpreting pp-values, remember that a low pp-value indicates strong evidence against the null hypothesis, while a high pp-value suggests weak evidence.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Normal Distribution
Standard Deviation
Z-score

Formulas

Z-score formula

Theorems

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Suitable Grade Level

Advanced