Exhibit 7-4: a Group of Researchers Has Developed a Method

question 28

Multiple Choice

Exhibit 7-4: A group of researchers has developed a method that they hypothesize will improve physics test scores.They randomly selected nine students to participate in their study.The nine students were administered an ACT test, trained in the new method, and then administered an alternate form of the ACT test.The following data are their scores:
$\begin{array}{lll}\text {Subject } & {\text {Test 1 }}{} & \text {Test 2 } \\ 1 & 20 & 19 \\ 2 & 20 & 20 \\ 3 & 24 & 21 \\ 4 & 24 & 24 \\ 5 & 24 & 22 \\ 6 & 17 & 15 \\ 7 & 18 & 15 \\ 8 & 18 & 16 \\ 9 & 20& 18\end{array}$
-Refer to Exhibit 7-4.What is the null hypothesis?

• A) \(\mu\)_{Test 1} \(\geq\)\(\mu\)_{Test 2}
• B) \(\mu\)_{Test 1} \(\leq\) \(\mu\)_{Test 2}
• C) \(\mu\)_{Test 1} = \(\mu\)_{Test 2}
• D) None of these are true.

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Definitions:

Food Chain

The series of organisms through which energy flows in an ecosystem. Each organism in the series eats or decomposes the preceding organism in the chain.

Competitive Exclusion

A principle stating that two species competing for the same limiting resources cannot coexist at constant population values.

Character Displacement

The phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are minimized or lost where the species' distributions do not overlap.

Primary Succession

An ecological succession that occurs on land that has not previously been inhabited by plants; no soil is present initially. See succession. Compare with secondary succession.