9.40 In an article published in a British medical journal, Japanese researchers
ID: 2960094 • Letter: 9
Question
9.40 In an article published in a British medical journal,Japanese researchers found that adults who were
videotaped in a relaxed setting blinked an average of
15.0 times per minute. Under the assumption that this
finding was based on the sample data in file XR09040,
construct and interpret the 99% confidence interval for
the population mean. Based on this confidence interval,
would it seem very unusual if another sample of this
size were to exhibit a mean blink rate of 16.0 times per
minute?
File XR09040:
bpm
15.5
17.3
17.6
14.9
16.1
15.5
14.3
14.1
15.1
7.0
11.0
17.9
17.2
14.9
15.9
17.1
12.8
16.5
17.0
14.0
14.7
12.8
12.2
17.8
14.7
18.0
13.4
17.2
16.2
13.4
17.8
15.0
12.6
16.5
11.0
Explanation / Answer
sample mean = 15 standard deviation = 2.417 99% CI = (15-t(0.0049, 34)*2.417/sqrt(35), 15+t(0.005, 34)*2.417/sqrt(35)) = (15-2.73*2.417/sqrt(35), 15+2.73*2.417/sqrt(35)) = (13.885, 16.115) 16 is within the 99% confidence interval Therefore it wouldn't be out of the ordinary for this to be reproduced at the same size
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