High School

A recent survey of 8,000 high school students found that the mean price of a prom dress was [tex]$\$195.00$[/tex] with a standard deviation of [tex]$12.00$[/tex]. Alyssa thinks that her school is more fashion-conscious and that students spent more than [tex]$\$195.00$[/tex]. She collected data from 20 people in her high school and found that the average price spent on a prom dress was [tex]$\$208.00$[/tex].

Which of the following are the correct null hypothesis and alternate hypothesis?

A. [tex]H_0: \mu = 195; \, H_a: \mu > 195[/tex]

B. [tex]H_0: \mu \neq 195; \, H_a: \mu = 208[/tex]

C. [tex]H_0: \mu = 195; \, H_a: \mu \neq 195[/tex]

D. [tex]H_0: \mu < 195; \, H_a: \mu \geq 208[/tex]

Answer :

To solve this problem, we need to establish the correct null and alternate hypotheses based on the information provided:

1. Understanding the Context:
- We are told that the mean price of a prom dress across a large survey of 8,000 high school students is [tex]$195.00, with a standard deviation of $[/tex]12.00.
- Alyssa suspects that students at her school spend more on prom dresses, with her data from 20 students showing an average of [tex]$208.00.

2. Hypothesis Testing Basics:
- The null hypothesis (H₀) is a statement of no effect or no difference. In this context, it represents the status quo, which is the mean price of a prom dress being $[/tex]195.00 for high school students generally.
- The alternate hypothesis (Hₐ) is what you want to test; in this case, Alyssa's suspicion that students at her school spend more on prom dresses.

3. Setting up the Hypotheses:
- Null Hypothesis (H₀): The mean price of a prom dress is [tex]$195.00. This can be expressed as \( H₀: \mu = 195 \).
- Alternate Hypothesis (Hₐ): Alyssa believes that students at her school spend more than the average on prom dresses. This is expressed as \( Hₐ: \mu > 195 \).

4. Choosing the Hypotheses:
- Given Alyssa's belief that students spend more than the reported average, we want to test if the mean price is greater than $[/tex]195. Therefore, the correct pair of hypotheses is:
- [tex]\( H₀: \mu = 195 \)[/tex]
- [tex]\( Hₐ: \mu > 195 \)[/tex]

This matches the first option provided in the list:
- [tex]\( H _0: \mu=195 ; H _a: \mu>195 \)[/tex]

Hence, this is the correct null and alternate hypothesis for this scenario.