STATS Chapters 1 + 2

formula for relative frequency (ex. rolling a dice)

# of times x landed face up _______________________________________ total # of times die was rolled

The score made by a particular student on a national standardized exam is the 65th percentile. This means that:

About 65% of all scores on the exam were lower than his.

A mother is told that her 13 year old son's height is the 85th percentile. This implies that:

Her son's height is more than that of 85% of all 13 year old boys.

relative frequency

a class of measurements is the proportion of all measurements in the data set that are included in that class.

symmetry

a distribution is symmetric when the mean is equal to the median.

statistic

a number computed from sample data.

parameter

a number that summarizes some aspect of the population.

The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 1600 randomly selected students; 451 had such jobs. The population of interest to the Department of Education is:

all college students

population

any specific collection of objects of interest.

sample

any subset of the population.

the empirical rule

applicable to bell-shaped curves.

determining whether data is skewed left/right:

fat tail falls to the direction the distribution is skewed.

Chebyshev's Theorem

for any numerical data set, at least 1-1/k^2, of the data lies within k std. dev. of the mean.

frequecy

how often a value, x, appears in the data set. (answer should be in decimal or percentage form.)

What percentage of the data lies between x and y? (formula for Chebyshev's)

k= x-mean _____________ std. dev.

skewed left

mean < median

skewed right

mean > median

know how to find:

mean, median, mode, range

standard deviation

measures the variability of data in a numerical data set.

sample mean formula

sum of x __________________ n- sample size

A statistics professor wishes to estimate how much time Introduction to Statistics students spend studying for an exam. She emailed 270 randomly selected Introduction to Statistics students, and the average time spent by these students to study for an exam was 12 hours. The sample selected by this statistics professor is:

the 270 students emailed.

quantitative data

the average number of children in a household.

qualitative data

the fastest animal on earth.

z-score formula

z= x - mean _______________ std. dev.