a percentage bar graph is sometimes used like a circle graph. If the bar is 8 cm, how long is each piece?

Depends. Are all pieces equal? How many pieces are there?

Sounds like there is a circle graph you have to look at first.

To find the length of each piece in a percentage bar graph, we need to know the total percentage represented by the entire bar. Once we know the total percentage, we can divide it by the number of pieces to find the length of each piece.

Let's say the entire bar represents 100%. If the bar graph is being used like a circle graph, with a complete circle representing 100%, then the length of the bar is 8 cm. We can use this information to find the length of each piece.

If the bar represents 100%, and it is 8 cm long, we can set up a proportion to find the length of each piece:

Length of each piece / Total percentage = Length of the bar / Total percentage

Let's say we have 4 pieces on the bar. We can set up the proportion as follows:

Length of each piece / 100% = 8 cm / 100%

Now, solve the proportion by cross-multiplying:

Length of each piece * 100% = 8 cm * 100%

Simplifying,

Length of each piece = (8 cm * 100%) / 100%

Canceling out the percentage,

Length of each piece = 8 cm

So, in this case, since the bar is 8 cm and represents 100%, each piece would also be 8 cm in length.