Question

Consumer Reports posts reviews and ratings of a variety of products on its website. The following is a sample of 20 speaker systems and their ratings. The ratings are on a scale of 1 to 5, with 5 being best.

Speaker                                             Rating                        Speaker                                   Rating

Infinity Kappa. 6.1                         4.00                   ACI Sapphire III                              4.67

Allison One                                     4.12                   Bose 501 Series                             2.14

Cambridge Ensemble II                3.82                   DCM KY-212                                   4.09

Dynaudio Contour 1.3                  4.00                   Eosone RSF 1000                           4.17

Hsu Rsch. HRSW 12V                    4.56                   Joseph Audio RM7 si                    4.88

Legacy Audio Focus                       4.32                   Martin Logan Aerius                     4.26

Mission 73Ii                                    4.33                   Omni Audio SA 12.3                      2.32

PSB 400i                                          4.50                   Polk Audio RT 12                           4.50

Snell Acoustics D IV                       4.64                   Sunfire True Subwoofer               4.17

Thiel CS 1.5                                     4.20                   Yamaha NS- A636                          2.17

1. Compute the mean and the median.
2. Compute the first and third quartiles.
3. Compute the standard deviation.

I just need Part C

Answer 1

Solution:

The formula for finding the standard deviation is: