An article in the Journal of Composite Materials (Vol. 23, 1989, p. 1200) describes the effect of delamination on the natural frequency of beams made from composite laminates. Five such delaminated beams were subjected to loads, and the resulting frequencies were as follows (in Hz): 230.66, 233.05, 232.58, 229.48, 232.58

Find a 90% two-sided CI on mean natural frequency. Do the results of your calculations support the claim that mean natural frequency is 235 Hz? Discuss your findings and state any necessary assumptions.