Number 12

11. The table below gives the distribution of students at a certain high school for two categorical cafeteria?" variables, grade year and the student's answer to the question, "Do you eat regularly in the school Grade 9th 10th 1 1 th 12th Totals Eat in YES 130 175 122 68 495 cafeteria? NO 18 34 38 170 310 Totals 148 209 210 238 805 a) If you choose a student at random, what is the probability he or she eats regularly in the cafeteria? b) If you choose a student at random, what is the probability he or she eats regularly in the cafeteria, given that he or she is in 10th grade? c) If you choose a student at random, are the events "10" grade" and "eats regularly in the cafeteria" independent? Explain how you know. 12. Your statistics class has 26 students in it-14 girls and 12 boys. Your teacher uses a calculator to select two students at random to solve a problem on the board. (a) What is the probability that both students are girls