3. An investigator draws a histogram for some height data, using the metric system. She is working in centimeters (cm). The vertical axis shows density, and the top of the vertical axis is 10 percent per cm. Now she wants to convert to millimeters (mm). There are 10 millimeters to the centimeter. On the horizontal axis, she has to change 175 cm to mm, and 200 cm to mm. On the vertical axis, she has to change 10 percent per cm to percent per mm, and 5 percent per cm to percent per mm. 42 THE HISTOGRAM [CH. 3]