Outliers, and choosing the best measure of center and spread

Answer Key - Grade 9 Math Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Jun recorded twelve library visits in minutes. The values are not in order. How many of them are outliers by the 1.5 × IQR rule?

   2
2. 2.

   Kira counted jump rope skips in a minute for twelve classmates. The values are not in order. How many of them are outliers by the 1.5 × IQR rule?

   2
3. 3.

   Luz measured twelve sunflowers in cm. The values are not in order. How many of them are outliers by the 1.5 × IQR rule?

   1
4. 4.

   Milo listed the pages in twelve library books. The values are not in order. How many of them are outliers by the 1.5 × IQR rule?

   2
5. 5.

   Noah timed eight maze runs in minutes. The run of 39 minutes is an outlier. When it is removed, how much more does the mean drop than the median?

   2.5
6. 6.

   Pia measured eight bean sprouts in mm. The sprout of 52 mm is an outlier. When it is removed, how much more does the mean drop than the median?

   2.75
7. 7.

   Ren counted skips in 30 seconds for eight classmates (one rope tangled). The count of 7 skips is an outlier. When it is removed, how much more does the mean rise than the median?

   2.25
8. 8.

   Tala recorded eight quiz scores out of 40. The score of 6 points is an outlier. When it is removed, how much more does the mean rise than the median?

   2.625
9. 9.

   Ari measured bean plants from two windowsills, eight each, in cm. Group A has one outlier, 47. Which statement compares the two groups fairly?

   • B's typical height is taller (medians 26 and 24.5), and A's middle half is less spread (IQRs 3 and 8).
   • B's typical height is taller (medians 26 and 24.5), and A is more spread out (ranges 27 and 14).
   • A's typical height is taller (means 26.75 and 26), and A's middle half is less spread (IQRs 3 and 8).
   • A's typical height is taller (medians 24.5 and 26), and B's middle half is less spread (IQRs 8 and 3).
10. 10.

    Bo recorded paper airplane flights for two teams of eight, in meters. Group A has one outlier, 24. Which statement compares the two groups fairly?

    • B's typical flight is longer (medians 9.5 and 8.5), and A's middle half is less spread (IQRs 3 and 6).
    • A's typical flight is longer (means 10 and 9.125), and A's middle half is less spread (IQRs 3 and 6).
    • A's typical flight is longer (medians 8.5 and 9.5), and B's middle half is less spread (IQRs 6 and 3).
    • B's typical flight is longer (medians 9.5 and 8.5), and A is more spread out (ranges 19 and 10).