UA · Unit 7 review

1. 1.

   A bag has 3 red and 5 blue marbles. One marble is drawn at random. P(red)?

   Answer. 38

   Favorable 3 / total 8 = 38.

2. 2.

   A spinner is spun 40 times and lands on green 24 times. What is the experimental probability of green?

   Answer. 35

   2440 = 35.

3. 3.

   A fair six-sided die is rolled. P(odd)?

   Answer. 12

   3 favorable outcomes out of 6 → 12.

4. 4.

   A bag has 4 green marbles out of 8. Two marbles are drawn with replacement. P(both green)?

   Answer. 14

   48 × 48 = 14.

5. 5.

   A bag has 3 red and 6 blue marbles. One marble is drawn at random. P(red)? Then Owen needs 2 of that amount. What is the total they need?

   Answer. 23

   Favorable 3 / total 9 = 13. Then multiply by 2: 23.

6. 6.

   A spinner is spun 80 times and lands on green 27 times. What is the experimental probability of green? Then Theo needs 3 of that amount. What is the total they need?

   Answer. 1180

   2780 = 2780. Then multiply by 3: 1180.

7. 7.

   A fair six-sided die is rolled. P(even)? Then Theo needs 4 of that amount. What is the total they need?

   Answer. 2

   3 favorable outcomes out of 6 → 12. Then multiply by 4: 2.

8. 8.

   A bag has 4 green marbles out of 8. Two marbles are drawn without replacement. P(both green)? Then Theo needs 5 of that amount. What is the total they need?

   Answer. 1114

   48 × 37 = 314. Then multiply by 5: 1114.

9. 9.

   A bag has 4 red and 4 blue marbles. One marble is drawn at random. P(red)? Then Priya needs 2 of that amount. What is the total they need?

   Answer. 1

   Favorable 4 / total 8 = 12. Then multiply by 2: 1.

10. 10.

    A spinner is spun 50 times and lands on green 14 times. What is the experimental probability of green? Then Sam needs 5 of that amount. What is the total they need?

    Answer. 125

    1450 = 725. Then multiply by 5: 125.

11. 11.

    Think

    Grace tried this problem:
    A fair six-sided die is rolled. P(1 or 2)?
    Grace wrote 14. That is not correct. What is the right answer?

    Answer. 13

    Grace’s answer 14 is off. 2 favorable outcomes out of 6 → 13.

12. 12.

    Think

    Sam tried this problem:
    A bag has 3 green marbles out of 6. Two marbles are drawn without replacement. P(both green)?
    Sam wrote 16. That is not correct. What is the right answer?

    Answer. 15

    Sam’s answer 16 is off. 36 × 25 = 15.

Original extra practice. Keys are computed from the items, not guessed.