Question

The length of each edge of a cube is decreased by 40 percent By what percent does the volume of the cube decrease? Express your answer to the nearest tenth.

Answer 1

Answer:

78% (to the nearest tenth)

Step-by-step explanation:

Volume of a cube = (length )³

Let the length of the cube = y

Original volume = y³

if the length is decreased by 40%, then new length = 1- (40% of y)

                                                                                     = 1-0.4y

                                                                                     =  0.6%

New volume (after decreasing the length) = (0.6y)³

                                                                      =  0.216‬‬y³

% Volume decrease = (Original volume - New volume)/Original Volume x 100%

                                 =  (y³ - 0.216‬‬y³)/ y³  x 100%

                                 = 0.784y³/y³  x 100%

                                 =78.4%

                                ≈78%

Answer 2

Answer:

  78.4%

Step-by-step explanation:

After the decrease, the edge length is 0.6 of what it was. Then the volume is 0.6^3 = 0.216 of what it was. That's a decrease of ...

  1 - 0.216 = 0.784 = 78.4%

The volume of the cube has decreased 78.4%.