15. A random force T is applied to pull a bookmark with a width of 1 in. The weight of the book is W ~ N(12, 0.15²) lb, and the coefficient of static friction between the bookmark and the paper is µ_s=0.6. If the pages are 8 in. (width) by 10 in. (length), determine the distribution of the minimum force that will make the bookmark start to move out. Assume the pressure on each page and the bookmark is uniform.

Solution: The minimum force is .