Pls help me pl. Bella measured the heights of her corn stalks in centimeters. The heights are 81, 88, 69,65, 87. What is the mean height of Bella's corn stalks? ——————————
O A 69 cm
O B. 75 cm
O C. 78 cm
OD 80 cm
O E 81 cm

the answer is C. 78

Step-by-step explanation:

First, you have to add together 81, 88, 69, 65, and 87; its total is 390. The next step is to see how many numbers there are. In total there are 5 numbers. Lastly, you have to divide 390 by 5 which is 78.

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.

it’s the first one your welcome