Customers of a phone company can choose between two service plans for long distance calls. The first plan has a $28 monthly fee and charges an additional $0.07 for each minute of calls. The second plan has a $14 monthly fee and charges an additional $0.12 for each minute of calls. For how many minutes of calls will the costs of the two plans be equal?

If sec theta = 5/3 and the terminal point determined by theta is in quadrant 4, then

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Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.