short-answer question is worth 3 marks. This section includes both numerical and written answers. For numerical answers, show your calculations in the space provided and round your answers to exactly four decimal places. Trailing zeros are not required. For written questions, type one word only. A visual memory test shows that when young adults (mean age 24 years) try to memorize 20 line drawings of common objects, they recognize 15 of these, on average, in a surprise test four weeks later. This population of scores is normal with a standard deviation of 2.4. A researcher was interested in whether older adults perform better on the task compared to young adults. Therefore, he chose a random sample of 36 older adults (mean age 71.2 years) and had them do the same task. Note that you can write <, instead of u, as the population mean; and , instead of o as the population standard deviation. a. State the null hypothesis in symbols. Ho: b. State the alternative hypothesis in symbols. H1: c. The older adults correctly recognized a mean of 15.7 items. Calculate zobs. First, write your calculation: Then, write your answer: d. What p-value is associated with Zobs? Please, write 4 decimal points. p = e. If we adopt the p < .05 significance level, is Zobs statistically significant? (yes/no) f. Should you retain or reject Ho? (retain/reject)