Standard deviation of a whole group and of a sample

Answer Key - Grade 11 Math Worksheet - Challenge Me

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

1. 1.

   Ari logs piano practice on 4 random days: 3, 5, 7 and 9 minutes, with mean 6. These are a sample. What is the sample standard deviation?

   2.58
2. 2.

   Bo counts birds at a feeder on 4 random mornings: 10, 12, 14 and 20, with mean 14. These are a sample. What is the sample standard deviation?

   4.32
3. 3.

   A whole group's data are 2, 4, 4, 4, 5, 5, 7, 9, with mean 5. What is σ, Jun?

   • 4
   • 2.14
   • 2
4. 4.

   Kira's whole-group variance is 9. What is σ?

   • 4.5
   • 3
   • 81
5. 5.

   Which of Luz's data sets has σ = 0?

   • 1, 2, 3, 4
   • 6, 6, 6, 6
   • 0, 0, 1, 1
6. 6.

   Noah says the SD of a whole class's 28 heights should divide by 27. Agree or disagree?

   • Agree: 27 makes it smaller
   • Disagree: a whole group uses 28
   • Agree: n − 1 is used for any SD
7. 7.

   Pia says a standard deviation can be negative. Agree or disagree?

   • Agree: values below the mean count
   • Disagree: it is a root of squares
   • Agree: when the mean is negative
8. 8.

   Ren's sample of reading times has mean 20 minutes and s = 3 minutes. How many SDs above the mean is 26 minutes?

   • 3
   • 6
   • 2
9. 9.

   Two classes have the same mean quiz score, with s = 2 and s = 8. Which is more consistent, Tala?

   • The class with s = 2
   • The class with s = 8
   • They are equal
10. 10.

    In Zee's data, one value moves farther from the mean while the mean stays put. What happens to the SD?

    • It stays the same
    • It increases
    • It decreases