L31 · Median and interquartile range

1. 1.

   Find the median of 8, 9, 10, 12, 14, 15, 17.

   Answer. 12

   Ordered already. Middle value is 12.

2. 2.

   Find the median of 5, 6, 7, 9, 11, 12, 14.

   Answer. 9

   Ordered already. Middle value is 9.

3. 3.

   Find the IQR of 7, 8, 9, 11, 13, 14, 16.

   Answer. 6

   Q1 = 8, Q3 = 14, IQR = 14 − 8 = 6.

4. 4.

   Find the median of 8, 9, 10, 12, 14, 15, 17.

   Answer. 12

   Ordered already. Middle value is 12.

5. 5.

   Find the IQR of 6, 7, 8, 10, 12, 13, 15. Then Ava needs 4 of that amount. What is the total they need?

   Answer. 24

   Q1 = 7, Q3 = 13, IQR = 13 − 7 = 6. Then multiply by 4: 24.

6. 6.

   Find the median of 4, 5, 6, 8, 10, 11, 13. Then Malik needs 5 of that amount. What is the total they need?

   Answer. 40

   Ordered already. Middle value is 8. Then multiply by 5: 40.

7. 7.

   Find the IQR of 4, 5, 6, 8, 10, 11, 13. Then Sam needs 2 of that amount. What is the total they need?

   Answer. 12

   Q1 = 5, Q3 = 11, IQR = 11 − 5 = 6. Then multiply by 2: 12.

8. 8.

   Find the IQR of 10, 11, 12, 14, 16, 17, 19. Then Luis needs 3 of that amount. What is the total they need?

   Answer. 18

   Q1 = 11, Q3 = 17, IQR = 17 − 11 = 6. Then multiply by 3: 18.

9. 9.

   Find the IQR of 6, 7, 8, 10, 12, 13, 15. Then Sam needs 2 of that amount. What is the total they need?

   Answer. 12

   Q1 = 7, Q3 = 13, IQR = 13 − 7 = 6. Then multiply by 2: 12.

10. 10.

    Find the IQR of 9, 10, 11, 13, 15, 16, 18. Then Priya needs 3 of that amount. What is the total they need?

    Answer. 18

    Q1 = 10, Q3 = 16, IQR = 16 − 10 = 6. Then multiply by 3: 18.

11. 11.

    Think

    Grace tried this problem:
    Find the IQR of 7, 8, 9, 11, 13, 14, 16.
    Grace wrote 12. That is not correct. What is the right answer?

    Answer. 6

    Grace’s answer 12 is off. Q1 = 8, Q3 = 14, IQR = 14 − 8 = 6.

12. 12.

    Think

    Malik tried this problem:
    Find the median of 7, 8, 9, 11, 13, 14, 16.
    Malik wrote 22. That is not correct. What is the right answer?

    Answer. 11

    Malik’s answer 22 is off. Ordered already. Middle value is 11.

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