Basic Concepts in Statistics Quiz: Classification of Variables and Sampling Methods

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Questions and Answers

What is Dillon's GPA/GWA for the given semester?

  • 3.7
  • 2.0
  • 2.5 (correct)
  • 3.0

In a Statistics Quiz Bee, the ages of five contestants are: 18, 17, 18, 19, and 18. What is their average age?

  • 18 (correct)
  • 16
  • 19
  • 17

When seven mothers had a blood pressure check, the recorded values were: 415, 398, 402, 400, 420, 415, 407, and 425. What is the median blood pressure?

  • 400
  • 420
  • 410
  • 415 (correct)

Ten physics students had exam scores of: 23, 45, 50, 23, 26, 28, 40, 23, 40, and 40. What is the mode of their scores?

<p>40 (Unimodal) (B)</p> Signup and view all the answers

What type of data distribution is observed when analyzing the scores of the ten physics students in their exam?

<p>Unimodal (A)</p> Signup and view all the answers

Based on the recorded ages of the five contestants in a Statistics Quiz Bee (18, 17, 18, 19, and 18), which contestant is the oldest?

<p>19 years old (D)</p> Signup and view all the answers

What is the weighted mean of the following values: $3 imes 4 + 4 imes 3 + 1 imes 3 + (2 imes 4)$?

<p>$14$ (C)</p> Signup and view all the answers

If Dillon's GPA for a particular semester was rounded to the nearest whole number, what would it be?

<p>$2$ (A)</p> Signup and view all the answers

Among the given recorded blood pressure values (415, 398, 402, 400, 420, 415, 407, and 425), which value is closest to the median?

<p>$407$ (B)</p> Signup and view all the answers

'14' was calculated as the weighted mean based on some values. Which two values were multiplied by $4$ to get this result?

<p>$3$ and $1$ (A)</p> Signup and view all the answers

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Study Notes

Statistics

  • Statistics is a collection of methods for planning experiments, obtaining data, and then analyzing, interpreting, and drawing conclusions based on the data.

Classification of Variables

  • Quantitative variables can be classified as:
    • Levels of measurement:
      • Nominal
      • Ordinal
      • Interval
      • Ratio

Measures of Central Tendency

Mean

  • The mean is a measure of central tendency that represents the average value of a dataset.
  • Example: Find the mean of six friends' test scores: 92, 84, 65, 76, 88, and 90.
    • σx = (92 + 84 + 65 + 76 + 88 + 90) / 6 = 82.5

Median

  • The median is the middle value in a dataset when it is arranged in order.
  • Example: Find the median of seven mothers' blood pressure readings: 135, 121, 119, 116, 130, 121, 131.
    • Arrange data in order: 116, 119, 121, 121, 130, 131, 135
    • Median = 121

Mode

  • The mode is the value that appears most frequently in a dataset.
  • Example: Find the mode of the given data set: 15, 28, 25, 48, 22, 43, 39, 44, 43, 49, 34, 22, 33, 27, 25, 22, and 30.
    • Arrange data in ascending order: 15, 22, 22, 22, 25, 25, 27, 28, 30, 33, 34, 39, 43, 43, 44, 48, 49
    • Mode = 22 (unimodal)
  • Example: Find the mode of the given data set: 2, 5, 8, 9, 11, 4, 7, 23.
    • No mode exists in this dataset.
  • Example: Find the mode of the given data set: 121, 110, 120, 119, 112, 121, 118, 115, 107, 115.
    • Arrange data in ascending order: 107, 110, 112, 115, 115, 118, 119, 120, 121, 121
    • Mode = 115 and 121 (bimodal)

Weighted Mean

  • The weighted mean is the average value of a dataset where each value has a corresponding weight or importance.
  • Formula: σ(x ∙ w) / σw
  • Example: Find the grade point average of Dillon's semester course grades:
    • English (B) = 3 units, History (A) = 4 units, Chemistry (D) = 3 units, Algebra (C) = 4 units
    • σ(x ∙ w) = (4 ∙ 3 + 3 ∙ 4 + 1 ∙ 3 + 2 ∙ 4) / (3 + 4 + 3 + 4) = 35 / 14 = 2.5

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