Question 305683
Eight college students were randomly divided into 2 groups of 4 each to test whether background music reduces studying capacity.  Each person was tasked with memorizing a list of 20 words.
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Group 1 had music playing through earphones they were wearing.  
Group 2 was not distracted.  
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The following are the number of words correctly remembered by each subject.  Test whether the music reduces studying capacity at a .05 level of significance.
Group 1 -- DISTRACTED	Group 2 – NOT DISTRACTED
Sample size = 4
Sample mean = 7
Sample std.dev. = 2.5
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Group 2 --- NOT DISTRACTED
Sample size = 4
Sample mean = 14
Sample std.dev. = 3.5

3a) Direction = UPPER TAILED / LOWER TAILED / 2-TAILED (circle one)
"Reduces" is the key word in the problem description:
Ans: left-tail test
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Note:
Ho: u(music)-u(no music) = 0
Ha: u(music)-u(no music) < 0 ("no music" helps)

3b) P-value = ________________
Test Statistic: 
t(7-14)= (-7)/sqrt[2.5^2/4 + 3.5^2/4] = -3.2549
p-value = P(t < -3.2549 when df = 5.4) = 0.0100
Note: I used a 2-sample T test on a TI calculator
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3c) REJECT THE NULL or DO NOT REJECT THE NULL? (Circle one)
Since the p-value is less than 5%, reject Ho
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3d) Can we conclude that music reduces studying capacity?
   YES or NO (circle one)
I'll leave that to you.
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Cheers,
Stan H.
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