Standard deviation of a whole group and of a sample

Answer Key - Grade 11 Math Worksheet - Building Confidence

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

1. 1.

   All 5 of Ari's soccer practices this week are timed. The squared distances from the mean add to 80. What is the standard deviation of this whole group?

   4
2. 2.

   Bo weighs all 4 pumpkins grown in a small garden patch. The squared distances from the mean add to 144. What is the standard deviation of this whole group?

   6
3. 3.

   Esme records the scores of all 10 players in a board-game club (one very cheerful winner). The squared distances from the mean add to 90. What is the standard deviation of this whole group?

   3
5. 4.

   Using the dot plot, how far is the value 9 from the mean, Jun?

   • 3
   • 6
   • 9
6. 5.

   Using the dot plot, what is the sum of the squared deviations, Kira?

   Use the picture in question 4.

   • 8
   • 0
   • 20
7. 6.

   Using the dot plot, why does Luz square the deviations before adding?

   Use the picture in question 4.

   • To make the mean come out bigger
   • So minus and plus don't cancel
   • To count the values twice
8. 7.

   Milo measures the heights of all 28 students in a class to describe that class. Whole group or sample?

   • Whole group: divide by n
   • Sample: divide by n − 1
   • Neither one
9. 8.

   Which symbol does Pia use for a sample's standard deviation?

   • n
   • s
   • σ
10. 9.

    Two of Ren's data sets have the same mean, but one has a larger SD. What does that show?

    • It has a larger mean value
    • It has more values
    • Its values are more spread out
11. 10.

    Tala's data set has a standard deviation of 0. What must be true?

    • There is just one value in it
    • The mean is 0
    • Every value is the same