Standardized measures seem to indicate that the average level of anxiety has increased gradually over the past 50 years. (Twenge, XXXXXXXXXXIn the 1950s , the average score on the Child Manifest...

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 μ= 15.1. A sample of n = 16 of today's children produces a mean score of M = 23.3 with SS = 240.

Based on the sample, has there been a significant increase in the average level of anxiety since the 1950s?
Use a one-tail test with α= .05.

Please answer the question using all of these steps: null in word, alternative in words, null in symbols, alternative in symbols, critical region t,  df,  all steps in the analysis computing your computed t, make a decision, and give a conclusion.

Do not skip around in the steps. Provide steps in an orderly steps by step manner.