Math Problem Statement

The scores on a sample of biology quizzes are: 2, 9, 5, 6, 6. Find the sample standard deviation of these biology quiz scores. Round to 2 decimal places.

Solution

To find the sample standard deviation for the biology quiz scores (2, 9, 5, 6, 6), we follow these steps:

Step 1: Find the mean

Mean=2+9+5+6+65=285=5.6\text{Mean} = \frac{2 + 9 + 5 + 6 + 6}{5} = \frac{28}{5} = 5.6

Step 2: Calculate the squared differences from the mean for each score

  • For 2: (25.6)2=(3.6)2=12.96(2 - 5.6)^2 = (-3.6)^2 = 12.96
  • For 9: (95.6)2=(3.4)2=11.56(9 - 5.6)^2 = (3.4)^2 = 11.56
  • For 5: (55.6)2=(0.6)2=0.36(5 - 5.6)^2 = (-0.6)^2 = 0.36
  • For 6: (65.6)2=(0.4)2=0.16(6 - 5.6)^2 = (0.4)^2 = 0.16
  • For the second 6: (65.6)2=(0.4)2=0.16(6 - 5.6)^2 = (0.4)^2 = 0.16

Step 3: Find the average of these squared differences

Variance=12.96+11.56+0.36+0.16+0.1651=25.24=6.3\text{Variance} = \frac{12.96 + 11.56 + 0.36 + 0.16 + 0.16}{5-1} = \frac{25.2}{4} = 6.3

Step 4: Take the square root of the variance

Standard Deviation=6.32.51\text{Standard Deviation} = \sqrt{6.3} \approx 2.51

Thus, the sample standard deviation is approximately 2.51.

Would you like more details or have any questions?

Here are 5 related questions to explore further:

  1. How does sample standard deviation differ from population standard deviation?
  2. Why do we divide by n1n - 1 in the sample variance formula?
  3. What are the properties of standard deviation in data sets?
  4. How would the standard deviation change if the data set had a different distribution?
  5. How can standard deviation be used to identify outliers in a data set?

Tip: Always remember to subtract 1 from the sample size when calculating sample variance to account for the degrees of freedom.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Variance

Formulas

Standard Deviation: sqrt((Σ(xi - mean)²) / (n - 1))
Mean: Σx / n

Theorems

Sample Standard Deviation Formula

Suitable Grade Level

Grades 9-12