1. Week #26 Bell Ringers & quiz 8 th grade math

2. Bell Ringer Monday On a recent test, 5 people made an A, 3 people made a B, 9 people made a C, and 3 people made an F. 1. What is the probability that a person chosen at random will have made an A? 2. What is the probability that a person chosen at random will not have made an A? 3. Calculate the median. 4. Calculate the mode. 5. Calculate the percent that made an F.

3. On a recent test, 5 people made an A, 3 people made a B, 9 people made a C, and 3 people made an F. 1. What is the probability that a person chosen at random will have made an A? 2. What is the probability that a person chosen at random will not have made an A?

4. On a recent test, 5 people made an A, 3 people made a B, 9 people made a C, and 3 people made an F. 3. Calculate the median. 4. Calculate the mode. 5. Calculate the percent that made an F.

5. Quiz Monday 4 different cubes are placed in a bag. If a cube is randomly pulled from the bag, what is the probability that the volume of the cube will be greater than 29 ft 3 ? cube 1 length = 2 ft cube 2 length = 3 ft cube 3 length = 4 ft cube 4 length = 5 ft

6. What is the probability of getting a volume greater than 29 cubic feet? I found the volume of each cube by multiplying the length of each cube by itself three times. I counted the number of volumes greater than 29. I wrote my probability placing the number of volumes greater than 29 over the total number of volumes. I reduced. 4 different cubes are placed in a bag. If a cube is randomly pulled from the bag, what is the probability that the volume of the cube will be greater than 29 ft 3 ? There is a 50% chance of pulling a cube with a volume greater than 29 cubic feet. cube 1 length = 2 ft cube 2 length = 3 ft cube 3 length = 4 ft cube 4 length = 5 ft volume cube 1 length = 2 ft cube 2 length = 3 ft cube 3 length = 4 ft cube 4 length = 5 ft

7. Bell Ringer Tuesday 1. What is the probability of spinning a blue and not drawing a blue marble? 2. What is the probability of spinning a blue or green and drawing a green marble? 3. What is the probability of drawing two blue marbles (without replacement)? 4. Is a probability of 3/8 or ¼ better?

8. 1. What is the probability of spinning a blue and not drawing a blue marble? 2. What is the probability of spinning a blue or green and drawing a green marble?

9. 3. What is the probability of drawing two blue marbles (without replacement)? 4. Is a probability of 3/8 or ¼ better?

10. Quiz Tuesday A software company employs 500 workers. It plans to decrease its workforce by 8 employees per month until it has cut its size in half. Which equation can be used to determine m, the number of months it will take for the company’s workforce to be cut in half? A. 8m - 500m = 250 B. 500 – 8m = 250 C..5(8m - 500) = 250 D. 500 –.5m = 250

11. Which equation can be used? In order to half the workers I divided the 500 current workers by two. If workers are subtracted each month, I would multiply -8 by the number of months. To get the total workers, I subtract the 8m to the 500. I found the equation that matched my work. A software company employs 500 workers. It plans to decrease its workforce by 8 employees per month until it has cut its size in half. Which equation can be used to determine m, the number of months it will take for the company’s workforce to be cut in half? Equation B can be used to calculate the number of months it will take to cut the workforce in half. 500 workers Subtract 8 workers per month half the size # months Half: 500/2 = 250 workers Decrease 8 workers/month = -8m Currently have 500 workers Total workers = 500 - 8m Equation B: 250 = 500 - 8m

12. Bell Ringer: Wednesday 1. What is the probability of spinning a red and drawing a red marble? 2. What is the probability of spinning a blue or green and drawing a yellow marble? 3. What is the probability of drawing a blue marble and then a green marble (without replacement)? 4. For the bag of marbles, calculate the mode.

13. 1. What is the probability of spinning a red and drawing a red marble? 2. What is the probability of spinning a blue or green and drawing a yellow marble?

14. 3. What is the probability of drawing a blue marble and then a green marble (without replacement)? 4. For the bag of marbles, calculate the mode.

15. Quiz Wednesday A software company employs 450 workers. It plans to increase its workforce by 8 employees per month until it has doubled in size. Which equation can be used to determine m, the number of months it will take for the company’s workforce to double in size? A. 8m + 450m = 900 B. 2m + 450 = 900 C. 2(8m + 450) = 900 D. 8m + 450 = 900

16. Which equation can be used? In order to double the workers I multiplied the 450 current workers by two. If workers are added each month, I would multiply 8 by the number of months. To get the total workers, I add the 450 to the 8m. I found the equation that matched my work. A software company employs 450 workers. It plans to increase its workforce by 8 employees per month until it has doubled in size. Which equation can be used to determine m, the number of months it will take for the company’s workforce to double in size? Equation D can be used to calculate the number of months it will take to double the workforce. 450 workers Add 8 workers per month Double in size # months Double: 450 (2) = 900 workers Add 8 workers per month = 8m Currently have 450 workers Total workers = 450 + 8m Equation D: 900 = 450 + 8m

17. Bell Ringer Thursday A bag contains 6 red marbles, 5 blue marbles, 3 green marbles, and 1 yellow marble. 1. What is the probability that a marble chosen at random will be blue? 2. What is the probability that a marble chosen at random will be yellow? 3. What is the probability that a marble chosen at random will not be red? 4. If a marble is pulled and replaced 100 times, how many red marbles can we expect to get? 5. Calculate the mode. 6. Calculate the range.

18. A bag contains 6 red marbles, 5 blue marbles, 3 green marbles, and 1 yellow marble. 1. What is the probability that a marble chosen at random will be blue? 2. What is the probability that a marble chosen at random will be yellow? 3. What is the probability that a marble chosen at random will not be red?

19. A bag contains 6 red marbles, 5 blue marbles, 3 green marbles, and 1 yellow marble. 4. If a marble is pulled and replaced 100 times, how many red marbles can we expect to get? 5. Calculate the mode. 6. Calculate the range.

20. Quiz Thursday Line segment d is a diagonal in each polygon shown below. Which drawing shows enough information to find the length of line segment d?

21. Which drawing can be used to find the length of the diagonal? I know that diagonals are associated with a hypotenuse. In order to solve for a hypotenuse, there must be a right triangle. I analyzed each drawing to see which one has a diagonal with a right triangle. Line segment d is a diagonal in each polygon shown below. Which drawing shows enough information to find the length of line segment d? Drawing H can be used to find the length of the diagonal. Diagonal Hypotenuse Location of d in each choice Diagonals = Hypotenuse To find the hypotenuse, the Pythagorean Theorem can be Used. To use the Theorem, there must Be a right triangle. Drawing H has the diagonal with a Right triangle.

22. Bell Ringer Friday Valdemar has a spinner with the numbers 1 through 5. He would like to increase the chances of the following events: Spinning an even number Spinning a number less than 4 Spinning the square root of 9 Valdemar decides to remove the 5 from the spinner. Which statement best supports his reasoning? A. The number 5 takes up more space on the spinner. B. Spinning the number 5 has the greatest probability. C. The number 5 is the greatest number. D. Spinning the number 5 is not a desired event. Explain why you did not choose the other three answer choices.

23. Valdemar has a spinner with the numbers 1 through 5. Valdemar would like to increase the chances of the following events: Spinning an even number Spinning a number less than 4 Spinning the square root of 9 Valdemar decides to remove the 5 from the spinner. Which statement best supports his reasoning? A. The number 5 takes up more space on the spinner. NO – Same chance as the others B. Spinning the number 5 has the greatest probability. NO – Same as the others C. The number 5 is the greatest number. TRUE – Would allow us to spin a number less than 4 D. Spinning the number 5 is not a desired event. TRUE – 5 has nothing to do with ANY of the criteria **Best Answer**

24. Quiz Friday 4 different cylinders are placed in a box. If a cylinder is randomly pulled from the box, what is the probability that the lateral surface area of the cylinder will be greater than 86 cm 2 ? cylinder 1: r = 2 cm; h = 3 cm cylinder 2: r = 2 cm; h = 4 cm cylinder 3: r = 3 cm; h = 4 cm cylinder 4: r = 3 cm; h = 5 cm

25. What is the probability of getting a surface area greater than 86 square centimeters? I found the surface area of each cylinder by multiplying the pi by 2 and multiplying that by the radius and height. I counted the number of areas greater than 86. I wrote my probability placing the number of areas greater than 86 over the total number of areas. I reduced. 4 different cylinders are placed in a box. If a cylinder is randomly pulled from the box, what is the probability that the lateral surface area of the cylinder will be greater than 86 cm 2 ? There is a 25% chance of pulling a cylinder with a surface area greater than 86 square centimeters. cylinder 1: r = 2 cm; h = 3 cm cylinder 2: r = 2 cm; h = 4 cm cylinder 3: r = 3 cm; h = 4 cm cylinder 4: r = 3 cm; h = 5 cm Lateral surface area