After further data collection the marketing manager (Exercise X6.4) decides to revisit the data analysis and changes the type of test to a t-test. (i) Explain under what conditions a t-test could be...

After further data collection the marketing manager (Exercise X6.4) decides to revisit the data analysis and changes the type of test to a t-test. (i) Explain under what conditions a t-test could be used rather  then  the z-test, and (ii) calculate the corresponding p-value if the sample size was 13 and the test statistic equal to 2.03. From this result what would you conclude?