1. The problem asks for the value below which 75% of the widths fall in the box plot. 2. In a box plot, the right edge of the box represents the 75th percentile (also called the third quartile, $Q_3$). 3. From the description, the right edge of the box is at about 35 cm. 4. Therefore, 75% of the widths were less than 35 cm. Final answer: 35 cm