Outliers, and choosing the best measure of center and spread

Answer Key - Grade 9 Math Worksheet

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

1. 1.

   Esme recorded twelve homework times in minutes. Use Q1 and Q3 (the middles of the two halves). What is the upper fence for outliers by the 1.5 × IQR rule?

   50
2. 2.

   Kira timed twelve walks to school in minutes. Use Q1 and Q3 (the middles of the two halves). What is the lower fence for outliers by the 1.5 × IQR rule?

   4.5
3. 3.

   Luz counted the pages twelve classmates read in a day. Use Q1 and Q3 (the middles of the two halves). What is the lower fence for outliers by the 1.5 × IQR rule?

   2.5
4. 4.

   Noah measured twelve tomato plants in cm. Which heights are outliers by the 1.5 × IQR rule?

   • Only 9
   • Only 31
   • No value is an outlier
   • 9 and 15
5. 5.

   Pia recorded twelve morning reading times in minutes. Which times are outliers by the 1.5 × IQR rule?

   • Only 38
   • No value is an outlier
   • 2 and 38
   • 2, 15, 27 and 38
6. 6.

   Ren listed twelve science quiz scores out of 50. Which scores are outliers by the 1.5 × IQR rule?

   • 31, 35, 45 and 50
   • No value is an outlier
   • Only 50
7. 7.

   Zee timed ten trips to school in minutes. Which pair of measures should Zee use to describe the center and the spread?

   • The mean and the standard deviation
   • The median and the IQR
   • The median and the standard deviation
8. 8.

   Ari measured ten pumpkin vines in meters. Which pair of measures should Ari use to describe the center and the spread?

   • The mean and the standard deviation
   • The median and the standard deviation
   • The median and the IQR
9. 9.

   Bo recorded ten violin practice times in minutes. Which pair of measures should Bo use to describe the center and the spread?

   • The median and the IQR
   • The median and the standard deviation
   • The mean and the standard deviation
10. 10.

    Esme timed ten paper boats floating across a pond, in seconds. Which pair of measures should Esme use to describe the center and the spread?

    • The mean and the standard deviation
    • The median and the IQR
    • The median and the standard deviation