I have self-studied the book “Probability and Statistics for Engineering and the Sciences 9th Edition”. From the following paragraph (about histogram construction) on the page 17
This construction ensures that the area of each rectangle is proportional to the relative frequency of the value. Thus if the relative frequencies of x=1 and x=5 are 0.35 and 0.07, respectively, then the area of the rectangle above 1 is five times the area of the rectangle above 5.
I am curious, why does the area of the rectangle above 1 deals with the five and the area of the rectangle above 5? why is it not width of the rectangle times 0.35 (which is hight)?
