Data Analysis Flashcards
Relative frequency
frequency count / total number
Relative frequencies added up = …
100% or 1
For quartiles, Q2 =
median
Q1 and Q3 are found by…
the median of the two halves around the median (Q2)
The interquartile range =
Q3 - Q1
How do you find standard deviation?
mean - value to the power of 2, add up all and find average, then take square root of this average
What is the difference between standard deviation (population standard deviation) and sample standard deviation?
sample standard deviation is found by dividing the sum of squared differences by n-1 instead of n
In any group of data, most data are within how many standard deviations above or below the mean?
3
multiplication principal: computer password consists of 4 characters such that the first letter one of 10 digits from
0-9 and each of the next are 3 characters from the alphabet
10(26)(26)(26)(26)
A U B
union of sets A and B: set A + set B - A&B
What is permutation formula?
N!
What is permutation formula if u select n objects taken k at a time?
N! / (N-K)!
Combination involves order or no order?
order doesn’t matter
Combination formula?
n!/k!(n-k)!
Each of the following linear equations defines y as a function of x for all integers x from 1 to 100. For which of the following equations is the standard deviation of the y-values corresponding to all the x-values the greatest.
y=x/3 y=x/2 + 40 y = x y = 2x + 50 y = 3x - 20
To answer, if the mean of x is m, then the mean of y is
am + b. So for x –> standard deviation involves [x-m] and for y it is [ax+b - am - b] or a[x-m]. Therefore for larger values of a, there is a larger distance between x and m. thus, 3x - 20 is the answer!
