a) If μ₁ is the average learning rate of the 6th graders without background noise level and μ₂ is the average learning rate of the 6th graders with the background noise level
The Null Hypothesis is that the learning rate of the 6th graders is not affected by the background noise level.
The null hypothesis, H₀: μ₁ = μ₂
b) The Alternative Hypothesis is that the learning rate of the 6th graders is affected by the background noise level.
An alternative hypothesis, Hа: μ₁ ≠ μ₂
c) Assumptions that must be met about the data before she can correctly use an independent t-test
There must be a random selection of the 6th graders
That the two groups are normally similar in their learning abilities
The division of students into the two groups should be at random
d) She has to make these assumptions to prevent bias and inaccuracy of results. If these assumptions are not made, the outcome of the experiment may not reflect the true effect of background noise on the learning of the 6th graders.
She can still get accurate results if she includes some bias in the selection to prove a particular result.
Learn more about the null hypothesis at
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