4. A university's financial aid office wants to know how much it can expect students to carn from summer employment. This information will be used to set the level of financial aid. The population contains 975 students who have completed at least one year of study but have not yet graduated. A questionnaire will be sent to a random sample of 50 of these students, drawn from an alphabetized list. (a) Explain clearly how you would use a random digits table to choose a simple random sample of 50 students from this population. (b) Beginning at line 120 in the random digits table below, show the first 10 students that are selected using the method described in part (b). Mark on the table or write below the table to show your method clearly. 120 35476 55970 39421 65850 04266 58435 43742 11937 121 71487 09984 29077 14863 61683 47052 62224 51025 122 13073 01590 95052 90908 73592 75186 07136 95761 (c) The survey is going to be conducted again the following academic year only this time they want to use a stratified random sample. Suggest a variable to stratify by. Justify your choice