Preliminary data analyses indicate that applying the z-test (Procedure 9.1 on page 388) in Exercises 9.83–9.88 is reasonable.
9.84 Grey-Seal Nursing. The average lactation (nursing) period of all earless seals is 23 days. Grey seals are one of several types of earless seals. The length of time that a female grey seal nurses her pup is studied by S. Twiss et al. in the article “Variation in Female Grey Seal (Halichoerus grypus) Reproductive Performance
At the 5% significance level, do the data provide sufficient evidence to conclude that the mean lactation period of grey seals differs from 23 days? Assume that the population standard deviation is 3.0 days.
(Note: The sum of the data is 274.9 days.)
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Introductory Statistics (10th Edition)
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