Question: (7 pt – dataset in Excel file) At what age do infants speak their first word of English? Here is the data for 20 children (age in months):

15 26 10 9 15 20 18 11 8 20

7 9 10 11 11 10 12 17 11 10

Do you have good evidence that the mean age at first word among all normal children is greater than 1 year?.

a. (1) State the (H0) and alternative hypotheses (Ha)

b. (2) Calculate the test statistic

c. (1) What are the degrees of freedom?

d. (1) What are the t-values that bracket your test statistic?

e. (1) Find your p-value.

f. (1) Make your final conclusion in words and in terms of the profile calculated p-value. Use 5% significance criteria.