10-42. An article in the Journal of Aircraft (Vol. 23, 1986, pp. 859-864) described a new equivalent plate analysis method formulation that is capable of modeling air- craft structures such as cranked wing boxes, and that produces results similar to the more computationally intensive finite element analysis method. Natural vi- bration frequencies for the cranked wing box structure are calculated using both methods, and results for the first seven natural frequencies follow: Finite Equivalent Element Plate, Freq. Cycle/'s Cycle/'s 14.58 14.76 48.52 49.10 97.22 99 99 113.99 117.53 174.73 181.22 212.72 220.14 277.38 294.80 (a) Do the data suggest that the two methods provide the same mean value for natu- ral vibration frequency? Use a = 0.05. Find the P-value. (b) Find a 95% confidence interval on the mean difference between the two methods