A water quality lab tests for the bacterial count in drinking water in a certain northern city. a) A test is made of a claim in the literature that the time to equilibrium in bacterial growth is greater in northerly climates, the standard deviation remaining unaffected. The mean time in southerly cities has been found, from many measurements, to equal 24.1 hours with a standard deviation of 2.3 hours. The northern lab tests 21 water specimens and finds the mean time to equilibrium bacterial growth is 25.4 hours, with an estimated stan- dard deviation of 2.2 hours, which is not significantly different from the standard deviation of 2.3 hours quoted above. Does this data bear out the claim in the literature about the increase in mean time to equilibrium, at the 5% level of significance? b) Two salesmen turn up at the laboratory one week, each claiming that the additive he is selling will decrease the time to equilibrium bacterial growth, compared to the other salesman's product. The laboratory decides to check out the claims and tests 6 specimens of water, half of each treated with each of the two products. You should neglect any possibility of interaction. What does the following data indicate as to the salesmen's claims (at the 5% level of significance)? Time to Equilibrium, hours Water Sample no. Additive I Additive 2 23.8 24.5 34.1 34.4 22.1 23.2 15.3 16.7 31.8 31.8 22.5 22.4

A researcher at a large company has collected data on the beginning salary and current salary of 50 randomly selected employees. The correlation between the data sets is r = 0.912. The summary statistics from the data collected are shown bellow:   Beginning Salary Ending Salary Mean x¯=56,340 y¯=82,070 Standard deviation Sx = 5,470 Sy = 7,800    Use a complete sentence to describe the strength and direction of the linear relationship between beginning salary and current salary.         Find the equation of the least-squares regression line. (Round to two decimal places)

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 2900 grams and a standard deviation of 900 grams while babies born after a gestation period of 40 weeks have a mean weight of 3400 grams and a standard deviation of 535 grams. If a 35-week gestation period baby weighs 3200 grams and a 40-week gestation period baby weighs 3700 grams, find the corresponding z-scores. Which baby weighs more relative to the gestation period? Find the corresponding z-scores. Which baby weighs relatively more? Select the correct choice below and fill in the answer boxes to complete your choice. (Round to two decimal places as needed.) A. The baby born in week 40 weighs relatively more since its z-score, baby born in week 35. B. The baby born in week 35 weighs relatively more since its z-score, baby born in week 40. C. The baby born in week 40 weighs relatively more since its z-score, baby born in week 35. D. The baby born in week 35 weighs relatively more since its z-score,…

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 2600 grams and a standard deviation of 600 grams while babies born after a gestation period of 40 weeks have a mean weight of 2800 grams and a standard deviation of 390 grams. If a 32​-week gestation period baby weighs 2150 grams and a 40​-week gestation period baby weighs 2350 ​grams, find the corresponding​ z-scores. Which baby weighs less relative to the gestation​ period?