1.
Which one is better: mean, median or mode?
Correct Answer
D. Depends on your goals
Explanation
Please read the following page for a more thorough explanation: http://www.shodor.org/interactivate/discussions/MeanMedianAndMode/
2.
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?
Correct Answer
A. 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.
3.
True or false: When the word
"mean" is used without a modifier, it can be assumed that it refers to
the arithmetic mean.
Correct Answer
A. True
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.
4.
The mean is the sum of all the scores _________
the number of scores.
Correct Answer
D. Divided by
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
5.
What is the standard deviation of the following (complete) population? 2, 4, 4, 4, 5, 5, 7, 9
Correct Answer
D. 2
Explanation
See here for an explanation: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example
6.
The difference in the formula for standard deviation between a complete population and an incomplete population is:
Correct Answer
D. Denominator minus 1
Explanation
See this link for more info: http://en.wikipedia.org/wiki/Standard_deviation#Basic_example
7.
To calculate standard deviation in Microsoft Excel, you first have to calculate the "average."
Correct Answer
A. True
Explanation
This is true. See: http://www.gifted.uconn.edu/siegle/research/Normal/stdexcel.htm
8.
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.
Correct Answer
A. True
Explanation
This is true. See: http://en.wikipedia.org/wiki/Normal_distribution#Definition
9.
Not all normal distributions are symmetric and
have bell-shaped density curves with a single peak.
Correct Answer
B. False
Explanation
This is false. By definition, all *normal* distributions are symmetric and have bell-shaped density curves with a single peak.
10.
For a normal distribution, almost all values lie within
___ standard deviations of the mean.
Correct Answer
D. 3
Explanation
If you got this incorrect, please review the section on normal distribution.
11.
Calculate normal distribution: If X is a normal random variable with mean (m) 100 and standard
deviation (σ) 6 find P(X<106)
Correct Answer
B. P = 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
12.
Using a z-table, determine the area
under the curve between 0 and 1.27
Correct Answer
A. 0.3962
Explanation
Please see this z-table and explanation of how to use it: http://www.easycalculation.com/statistics/normal-ztable.php