In a randomized comparative experiment on the effect of color on the performance

Question

In a randomized comparative experiment on the effect of color on the performance of a cognitive task, researchers randomly divided 72 subjects (30 males and 42 females ranging in age from 17 to 25 years) into three groups. Participants were asked to solve a series of 6 anagrams. One group was presented with the anagrams on a blue screen; one group saw them on a red screen; and one group had a neutral screen. The time, in seconds, taken to solve the anagrams was recorded. The paper reporting the study gives x¯¯¯=x¯= 11.54 and s=s= 4.47 for the times of the 25 members of the neutral group.

(Give your answer to three decimal places.)

A 98% confidence interval for the mean time in the population from which the subjects were recruited is from______ to ________ seconds.

PLEASE WRITE YOURE ANSWER AS REQUESTED FILL THE BLANK AS ANSWER A AND ANSWER B

Explanation / Answer

Confidence Interval
CI = x ± t a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
ta/2 = t-table value
CI = Confidence Interval
Mean(x)=11.54
Standard deviation( sd )=4.47
Sample Size(n)=72
Confidence Interval = [ 11.54 ± t a/2 ( 4.47/ Sqrt ( 72) ) ]
= [ 11.54 - 2.38 * (0.527) , 11.54 + 2.38 * (0.527) ]
= [ 10.286,12.794 ]

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