21. Statistics

Question 1

Mean

of {x₁, x₂, …, x_n}

Answer 1

Sum of all data values divided by the number of values.

Question 2

Median

Answer 2

Data must be ordered first.

Odd # of values: median is single middle value.

Even # of values: median is the mean of the two middle values.

Question 3

Mode

Answer 3

The value that appears most often.

Question 4

Range (measure of spread)

Answer 4

The difference between the largest and smallest data values.

Question 5

Z-score

Answer 5

The number of standard deviations s that a data value x is from the mean x^{<span>–</span>}

Question 6

Standard Deviation

of the values {x₁, x₂, …, x_n}

for a sample of the population.

Answer 6

Question 7

Standard Deviation on TI-89

of {5, 7, 9}

Answer 7

CATALOG → stdDev

Question 8

Regression

Answer 8

Relationship between two variables. A method for fitting a curve through a set of points.

Question 9

Regression models (general equations)

• Linear
• Quadratic
• Exponential

Answer 9

Linear model: y = a₀ + a₁x

Quadratic model: y = a₀ + a₁x + a₂x²

Exponential model: y = a₀e^{<em>a</em>₁<em>x</em>}

Question 10

Regression on TI-89

Answer 10