4. A study examined the effect of V-shaped notches on the strength of the amorphous glassy polymer polymethylmethacrylate. Notches were machined into beams (width = 28 mm, length 112 mm, thickness

- 14 mm) to a depth of 14mm with an angle of 30°. 16 beams were tested in three point bend tests and the maximum pressure (in N) recorded. The study reported (230.2, 249.8)N as the 95% confidence interval for the expected maximum pressure (using a known population standard deviation).