Math Problem Statement

Is there sufficient evidence to conclude that there is a linear correlation between imported lemon imports and crash fatality rates? Construct a scatterplot, compute the correlation coefficient, test statistic, and interpret results.

Solution

From the image, let's analyze and solve the problem step by step:

Step 1: Define the Hypotheses

  • The null hypothesis (H0H_0) and alternative hypothesis (H1H_1) relate to the population correlation coefficient (ρ\rho):
    • H0:ρ=0H_0: \rho = 0 (No linear correlation)
    • H1:ρ0H_1: \rho \neq 0 (A linear correlation exists) The correct option for the hypotheses is Option A.

Step 2: Scatterplot

From the given data:

  • Lemon Imports (x): 229, 266, 357, 480, 533
  • Crash Fatality Rate (y): 15.8, 15.6, 15.5, 15.2, 14.9

Looking at the scatterplots:

  • Option D is the correct scatterplot, as it shows a clear negative trend between the lemon imports and crash fatality rates.

Step 3: Calculate the Correlation Coefficient (r)

Using the formula for rr: [ r = \frac{n \sum (xy) - \sum x \sum y}{\sqrt{\left[n \sum x^2 - (\sum x)^2\right] \left[n \sum y^2 - (\sum y)^2\right]}} ]

Substitute the values:

  • n=5n = 5 (number of data points)
  • x=[229,266,357,480,533]x = [229, 266, 357, 480, 533]
  • y=[15.8,15.6,15.5,15.2,14.9]y = [15.8, 15.6, 15.5, 15.2, 14.9]

Perform the calculations for:

  1. x\sum x, y\sum y, xy\sum xy, x2\sum x^2, y2\sum y^2.
  2. Plug these into the formula for rr.

This will yield the linear correlation coefficient rr. Let me compute this for you.


Step 4: Test Statistic (t)

Once rr is calculated: t=rn21r2t = \frac{r \sqrt{n-2}}{\sqrt{1-r^2}} Substitute rr, n=5n = 5, and compute tt.


Step 5: P-value and Conclusion

Using the tt-value and degrees of freedom (df=n2=3df = n - 2 = 3):

  • Look up the p-value or use statistical software.
  • Compare the p-value to α=0.05\alpha = 0.05.
  • If pαp \leq \alpha, reject H0H_0, suggesting a significant linear relationship.

Let me calculate the values for rr, tt, and pp for the final answer. numpy as np from scipy.stats import t

Given data

x = np.array([229, 266, 357, 480, 533]) y = np.array([15.8, 15.6, 15.5, 15.2, 14.9])

Calculations for correlation coefficient r

n = len(x) sum_x = np.sum(x) sum_y = np.sum(y) sum_xy = np.sum(x * y) sum_x2 = np.sum(x2) sum_y2 = np.sum(y2)

Correlation coefficient formula

r = (n * sum_xy - sum_x * sum_y) / np.sqrt((n * sum_x2 - sum_x2) * (n * sum_y2 - sum_y2))

Test statistic t

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Math Problem Analysis

Mathematical Concepts

Linear Correlation
Scatterplots
Hypothesis Testing
Correlation Coefficient

Formulas

r = (n * Σ(xy) - Σx * Σy) / sqrt([(n * Σ(x^2) - (Σx)^2) * (n * Σ(y^2) - (Σy)^2)])
t = r * sqrt((n - 2) / (1 - r^2))

Theorems

Linear Correlation Hypothesis Testing

Suitable Grade Level

College/University Level