A cognitive psychologist wants to know whether memory performance is changed by old age. She randomly selects 19 elderly individuals and finds that their mean score on a standardized memory test equals 456.2. Scores on the standardized test in the general population are distributed normally with a mean equal to 478.8 and a variance equal to 2352.3 . Is there sufficient evidence to conclude that memory performance for elderly individuals differs from that of the general population? Use a significance level of 0.1 Step 1 of 2 : What is the value of P? Use four decimals in your answer.