Ap Stats Chapter 6.1

Front 1

random variable

Back 1

a variable taking numerical values determined by the outcome of a chance process.

Front 2

The Probability distribution of a random variable X tells us :

Back 2

what the possible values of x are and how probabilities are assigned to those values

Front 3

Discrete random variable

Back 3

has a fixed set of possible values with gaps between them. The probability distribution assigns each of these values a probability between 0 and 1 such that the sum of all the probabilities is exactly 1

Front 4

The probability of any event is...

Back 4

the sum of all the values that make up the event.

Front 5

Continuous random variable

Back 5

takes all values in some interval of numbers. A density curve describes the probability distribution of a continuous random variable.

Front 6

The probability of any event is the...

Back 6

area under the curve above the values that make up the event.

Front 7

mean of a random variable

Back 7

the balance point of the probability distribution histogram or density curve. Since the mean is the long run average value of the variable after many repetition of the chance process, it is also know as the expected value of a random variable.

Front 8

If X is a discrete random variable, the mean is:

Back 8

the average of the values of X each weighted by its probability.

Front 9

variance of a random variable

Back 9

the average squared deviation of the values of the variable from its mean.

Front 10

standard deviation of a random variable.

Back 10

the square root of the variance. The standard deviation measures the variability of the distribution about the mean.