The PH of a solution with a hydronium-ion concentration of mole per litre is given by PH= -log[H^+], A sample of blood has a PH of 7.3. Find the hydronium-ion concentration of blood?​

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

James was playing a game with his friends. he won 35 points. then he lost 15, lost 40 and won 55. how did he come out

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.