Standard deviation of a whole group and of a sample

Answer Key - Grade 11 Math Worksheet

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

1. 1.

   Ari times 5 randomly chosen school-bus rides to learn about all the rides. The squared distances from the sample mean add to 64. What is the sample standard deviation?

   4
2. 2.

   Bo weighs 9 apples picked at random from a big orchard crate. The squared distances from the sample mean add to 200. What is the sample standard deviation?

   5
3. 3.

   Esme measures 11 sunflowers chosen at random from a whole field (all of them showing off). The squared distances from the sample mean add to 90. What is the sample standard deviation?

   3
4. 4.

   Why does Jun divide by n − 1 for a sample?

   • A sample tends to understate the spread
   • Samples hold one bad value each
   • It makes the mean exact
5. 5.

   For the same data, how does Kira's s compare with σ?

   • s is a little smaller
   • s is a little larger
   • They are exactly equal
6. 6.

   A coach times all 12 players on Milo's team to describe this team. Which formula fits?

   • Divide by 2
   • Divide by n − 1
   • Divide by n
7. 7.

   Noah measures 20 fish from a lake to describe all the lake's fish. Which formula fits?

   • Divide by n
   • Divide by 20 squared
   • Divide by n − 1
8. 8.

   Pia checks 30 bottles from a factory's 5,000 made today. Which formula fits the 30?

   • Divide by n − 1
   • Divide by n
   • Divide by 5,000
9. 9.

   Set A is 4, 5, 6 and set B is 1, 5, 9. Which has the larger SD, Ren?

   • Set A
   • Set B
   • They tie
10. 10.

    Zee doubles every value in a data set. What happens to the SD?

    • It is multiplied by 4
    • It stays the same
    • It doubles