A New Study Has Found That,on Average,6- to 12-Year-Old Children

question 57

Multiple Choice

A new study has found that,on average,6- to 12-year-old children are spending less time on household chores today compared to 1981 levels.Suppose two samples representative of study's results report the following summary statistics for the two periods. 1981 Levels
2008 Levels 30 minutes 24 minutes
S₁ = 4.2 minutes
S₂ = 3.9 minutes
N₁ = 30
N₂ = 30
Using a 5% confidence level,which of the following is correct?

• A) Reject H₀: µ₁− µ₂ ≤ 0 and therefore do not conclude that relative to the 1981 levels,6- to 12-year-old children spent less time in 2008 on household chores.
• B) Do not rejectH₀: µ₁− µ₂ ≤ 0 and therefore conclude that relative to the 1981 levels,6- to 12-year-old children spent less time in 2008 on household chores.
• C) Reject H₀: µ₁− µ₂ ≤ 0 and therefore conclude that relative to the 1981 levels,6- to 12-year-old children spent less time in 2008 on household chores.
• D) Do not reject H₀: µ₁- µ₂ ≤ 0 and therefore do not conclude that relative to the 1981 levels,6- to 12-year-old children spent less time in 2008 on household chores.

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Definitions:

Pioneer Species

Pioneer species are the first to colonize previously disrupted or damaged ecosystems, starting a chain of ecological succession that leads to increased biodiversity.

Exotic Species

Species that are introduced to a new area where they do not naturally occur, often leading to ecological disruptions.

Indicator Species

Organisms used as a sign or measure of the environmental conditions or changes in an ecosystem because of their sensitivity to such conditions.

Endemic Species

Species that are native to a specific geographical area and are not naturally found anywhere else.