Standardized measures seem to indicate that the average level of anxiety has increased gradually over the past 50 years (Twenge, 2000). In the 1950s, the average score on the Child Manifest Anxiety Scale was = 14.1. A sample ofn= 15 of today's children produces a mean score ofM= 23.3 with SS= 240.Based on the sample, has there been a significant change in the average level of anxiety since the1950s? Use a two-tailed test with = 0.01.