A journal article reports that a sample of size 5 was used as a basis for calculating a 95% CI for the true average natural
frequency (Hz) of delaminated beams of a certain type. The resulting interval was (229.565, 233.303). You decide that a
confidence level of 99% is more appropriate than the 95% level used. What are the limits of the 99% interval? [Hint: Use
the center of the interval and its width to determine x and s.] (Round your answers to three decimal places.)
USE SALT
229.089
x 233.779
x) Hz
You may need to use the appropriate table in the Appendix of Tables to answer this question.
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A triathlon consisting of swimming, cycling, and running is one of the more strenuous amateur sporting events. An article
reports on a research study involving nine male triathletes. Maximum heart rate (beats/min) was recorded during
performance of each of the three events. For swimming, the sample mean and sample standard deviation were 186.0 and
7.3, respectively. Assuming that the heart-rate distribution is (approximately) normal, construct a 98 % CI for true mean
heart rate of triathletes while swimming. (Round your answers to one decimal place.)
179.3
USE SALT
x
192.7
xbeats/min
You may need to use the appropriate table in the Appendix of Tables to answer this question.
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