What is the standard deviation and variance of 100,100,120,120,180

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?

What three-dimensional solid have 6 rectangular faces, 2 equal bases that are not rectangles and 18 edges

In the diagram, bc¯¯¯¯¯∥de¯¯¯¯¯ . what is ce ? enter your answer in the box.