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The following data lists the ages of a random selection of actresses when they won an award in the category of Best Actress, along with the ages of actors when they won in the category of Best Actor. The ages are matched according to the year that the awards were presented. Complete parts (a) and (b) below.

[tex]
\[
\begin{tabular}{|l|llllllllll|}
\hline
Actress (years) & 25 & 29 & 31 & 26 & 34 & 28 & 29 & 43 & 32 & 31 \\
\hline
Actor (years) & 65 & 36 & 39 & 34 & 33 & 34 & 49 & 36 & 37 & 43 \\
\hline
\end{tabular}
\]
[/tex]

a. Use the sample data with a 0.05 significance level to test the claim that for the population of ages of Best Actresses and Best Actors, the differences have a mean less than 0 (indicating that the Best Actresses are generally younger than Best Actors).

In this example, [tex]\mu_d[/tex] is the mean value of the differences [tex]d[/tex] for the population of all pairs of data, where each individual difference [tex]d[/tex] is defined as the actress's age minus the actor's age. What are the null and alternative hypotheses for the hypothesis test?

[tex]H_0: \mu_d = 0 \, \text{year(s)}[/tex]

[tex]H_1: \mu_d \ \textless \ 0 \, \text{year(s)}[/tex]

(Type integers or decimals. Do not round.)

Answer :

Certainly! Let's analyze the problem step-by-step to understand the solution. We're testing a hypothesis about the ages of actresses and actors when they won Best Actress and Best Actor awards, respectively.

### Step 1: Understanding the Hypotheses
The problem asks us to test the claim that the ages of Best Actresses are generally younger than those of Best Actors.

- Null Hypothesis ([tex]\( H_0 \)[/tex]): The mean difference in ages ([tex]\( \mu_d \)[/tex]) between actresses and actors is zero or greater. Mathematically, [tex]\( \mu_d \geq 0 \)[/tex].
- Alternative Hypothesis ([tex]\( H_1 \)[/tex]): The mean difference in ages ([tex]\( \mu_d \)[/tex]) is less than zero. Mathematically, [tex]\( \mu_d < 0 \)[/tex].

### Step 2: Calculate the Differences
For each pair of ages from the actresses and actors, we calculate the difference:
[tex]\[
\text{Difference} = \text{Age of Actress} - \text{Age of Actor}
\][/tex]

Using the data provided:
- Actresses' ages: [25, 29, 31, 26, 34, 28, 29, 43, 32, 31]
- Actors' ages: [65, 36, 39, 34, 33, 34, 49, 36, 37, 43]

The list of differences computed would be:
[tex]\[
[-40, -7, -8, -8, 1, -6, -20, 7, -5, -12]
\][/tex]

### Step 3: Calculate the Mean of Differences
Next, we find the mean of these differences:
- Mean difference = [tex]\(-9.8\)[/tex]

### Step 4: Perform a Hypothesis Test
We conduct a one-sample t-test for the mean of these differences to determine if it's significantly less than zero.

The results of our t-test are:
- t-statistic: [tex]\(-2.42\)[/tex]
- p-value: [tex]\(0.019\)[/tex]

### Step 5: Make a Conclusion
Our significance level ([tex]\( \alpha \)[/tex]) is [tex]\(0.05\)[/tex]. We compare the p-value against the significance level:
- Since the [tex]\( \text{p-value} = 0.019 \)[/tex] is less than [tex]\( \alpha = 0.05 \)[/tex], we have enough evidence to reject the null hypothesis.

### Conclusion
We reject the null hypothesis, supporting the claim that Best Actresses are generally younger than Best Actors when they won the award. This analysis indicates a statistically significant difference in the mean ages, favoring that Best Actresses tend to be younger.

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