A Student Of Statistics? This Is A Quiz For You, Then!

1) The mean is the sum of all the scores _________ the number of scores.

Except for

Multiplied by

Subtracted from

Divided by

Except from

The mean is the sum of all the scores divided by the number of scores. The formula in summation notation is: μ = ΣX/N

Explanation

The mean is the sum of all the scores divided by the number of scores. The formula in summation notation is: μ = ΣX/N

2) True or false: When the word "mean" is used without a modifier, it can be assumed that it refers to the arithmetic mean.

True

False

The arithmetic mean is what is commonly called the average: When the word "mean" is used without a modifier, it can be assumed that it refers to the arithmetic mean. The mean is the sum of all the scores divided by the number of scores.

Explanation

The arithmetic mean is what is commonly called the average: When the word "mean" is used without a modifier, it can be assumed that it refers to the arithmetic mean. The mean is the sum of all the scores divided by the number of scores.

3) In probability theory and statistics, the normal distribution or Gaussian distribution is an absolutely continuous probability distribution with zero cumulants of all orders higher than two. The graph of the associated probability density function is bell-shaped, with a peak at the mean, and is known as the Gaussian function or bell curve.

True

False

This is true. See: http://en.wikipedia.org/wiki/Normal_distribution#Definition

Explanation

This is true. See: http://en.wikipedia.org/wiki/Normal_distribution#Definition

4) Which one is better: mean, median or mode?

Mean

Median

Mode

Depends on your goals

Please read the following page for a more thorough explanation: http://www.shodor.org/interactivate/discussions/MeanMedianAndMode/

Explanation

Please read the following page for a more thorough explanation: http://www.shodor.org/interactivate/discussions/MeanMedianAndMode/

5) To calculate standard deviation in Microsoft Excel, you first have to calculate the "average."

True

False

This is a trick question

This is true. See: http://www.gifted.uconn.edu/siegle/research/Normal/stdexcel.htm

Explanation

This is true. See: http://www.gifted.uconn.edu/siegle/research/Normal/stdexcel.htm

6) Not all normal distributions are symmetric and have bell-shaped density curves with a single peak.

True

False

This is false. By definition, all *normal* distributions are symmetric and have bell-shaped density curves with a single peak.

Explanation

This is false. By definition, all *normal* distributions are symmetric and have bell-shaped density curves with a single peak.

7) What is the median of the data set: 4, 3, 1, 2, 6, 3, 4, 5, 2, 6, 4, 3, 3, 3, 6, 4, 6, 4, 2, 6?

4

6

5

3.5

you sort the numbers first: 1, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6 eggs. There is an even number of values, so the middle (or median) is between the first and second 4 (the 10th and 11th values). Because they are the same, their average is also 4, so the median is 4.

Explanation

you sort the numbers first: 1, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6 eggs. There is an even number of values, so the middle (or median) is between the first and second 4 (the 10th and 11th values). Because they are the same, their average is also 4, so the median is 4.

8) The difference in the formula for standard deviation between a complete population and an incomplete population is:

Mean plus 1

Mean minus 1

Numerator minus

Denominator minus 1

See this link for more info: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example

Explanation

See this link for more info: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example

9) Calculate normal distribution: If X is a normal random variable with mean (m) 100 and standard deviation (σ) 6 find P(X<106)

P = 0.1

P = 0.8413

P = 94

There is not enough information to solve this problem.

Step 1: For a given value X=106
Z = (106-100)/6
= 1

Step 2: Find the value of 1 in Z table
Z = 1 = 0.3413

Step 3: Here the X value is greater than mean
P(X) = 0.5 + 0.3413 = 0.8413

Explanation

Step 1: For a given value X=106
Z = (106-100)/6
= 1

Step 2: Find the value of 1 in Z table
Z = 1 = 0.3413

Step 3: Here the X value is greater than mean
P(X) = 0.5 + 0.3413 = 0.8413

10) What is the standard deviation of the following (complete) population? 2, 4, 4, 4, 5, 5, 7, 9

4

4.5

5

2

There is not enough information to determine standard deviation

See here for an explanation: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example

Explanation

See here for an explanation: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example

11) For a normal distribution, almost all values lie within ___ standard deviations of the mean.

4

5

2

3

If you got this incorrect, please review the section on normal distribution.

Explanation

If you got this incorrect, please review the section on normal distribution.

12) Using a z-table, determine the area under the curve between 0 and 1.27

0.3962

0.4909

0.398

There is not enough information to answer this question

Please see this z-table and explanation of how to use it: http://www.easycalculation.com/statistics/normal-ztable.php

Explanation

Please see this z-table and explanation of how to use it: http://www.easycalculation.com/statistics/normal-ztable.php