Help plz what is 2 x 9

Paint should be stored and mixed in an osha-approved room with all of the following, except: a) adequate ventilation b) ventilation hoods c) unshielded electrical devices d) fire extinguishers

Which of the following must happen in order for productivity to increase? a. production levels remain unchanged while inputs increase. b. production levels rise while inputs decrease. c. production levels fall while inputs increase.

The difference between the observed value and the mean of the set of values is a