The psychologist claims that mean age at which children begin talking is 12.8 months. Carlos wished to check if claim is true. He took the random sample of 20 children and found that mean age at which children began talking was 13.9 months with the standard deviation of 1.8 month. Using 5% significance level, can you conclude that mean age at which children begin talking is different from 12.8 months? Suppose that ages at which all children begin talking have the approximately normal distribution.
i) How many degrees of freedom will you use for problem?
ii) Determine critical values for the hypothesis test
iii) Determine test statistic to.
iv) Determine p-value for this test
v) Use p-value to draw the conclusion.