Astore manager is looking at past jewelry sales to determine what sizes of rings to keep in stock. the list shows the ring sizes purchased by the last ten jewelry customers. 9, 7, 6.5, 7.5, 7, 8, 5, 6, 7.5, 8 what is the variance of the data set? round to the nearest hundredths. 0.40 0.72 1.15 2.14

(C)1.15

Step-by-step explanation:

The given data set is:

9, 7, 6.5, 7.5, 7, 8, 5, 6, 7.5, 8

In order to find the variance of the given data set, firstly find the mean of the data set.

Thus,

Now, Data set                                  

9                                                                          3.422

7                                                                          0.022

6.5                                                                       0.422

7.5                                                                       0.122

7                                                                          0.022

8                                                                          0.722

5                                                                          4.622

6                                                                          1.322

7.5                                                                       0.122

8                                                                          0.722

Now,

Thus, the variance of the given data set is 1.15.

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.