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Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population, find the population standard deviation, o.79828588912497

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

Which expression is rational? 6. , square root two, square root 14, square root 49