20, 16, 18, 14, 9, 20, 16

a. mean = 16;

standard deviation = 3.6

c. mean = 16;

standard deviation = 12.7

b. mean = 16.1;

standard deviation = 3.6

d. mean = 16.1;

standard deviation = 12.7

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

you bought 31 v bucks

step-by-step explanation:

25+6=31