#4

20 pencils I erasers Eraser Nocrater 9 mechanical 4 Both mecha mech plug NO 3 In 9-4 = (5 ) + Eraser. Total 13 20-7 =( 13) 13- 5 = (8 4. In the teacher's pencil box, 7 out of 20 pencils have an eraser, and 9 out of 20 are 20-9=10 7-47 3) mechanical pencils. 4 pencils are both mechanical and have an eraser on them. What is the probability that Ava chooses a pencil at random from the box and gets a. Mechanical pencil with an eraser? b. either a mechanical pencil or a pencil with a good eraser? 5. A student is taking two courses, Statistics and Economics. The probability that students will pass the statistics course is .83, and the probability of passing the economics course is 0.66. The probability of passing both is 0.62. a. What is the probability of passing at least one? . 6 6 +. 8 3 - 62 = 0.87 b. What is the probability of failing both? What is the probability of either passing the Statistics course or Economies course C . . 21+. 04 = / 0.25 but not both? possionly come