Stats 5-2

Question 1

STATS 5-2

random variable

Answer 1

a variable (typically represented by x) that has a numerical value, determined by chance, for each outcome of a procedure

Question 2

STATS 5-2

probability distribution

Answer 2

a description that gives the probability for each value of the random variable. It is often expressed in the format of a table, formula or graph.

Question 3

STATS 5-2

discrete random variable

Answer 3

has a collection of values that is finite or countable(if there are infinitely many values, the number of values is countable if it is possible to count them individually, such as the number of tosses of a coin before getting tails.

Question 4

STATS 5-2

Continuous random variable

Answer 4

infinitely many values and the collection of the values is not countable. (It is impossible to count the individual items because at least some of them are on a continuous scale) Time & Height

Question 5

STATS 5-2

probability distribution requirements

Answer 5

1. there is a numerical random variable x and its values are associated with corresponding probabilities
2. ∑P(x) = 1 where x assumes all possible values (the sum of all probabilities must be 1, but sums such as .999 or 1.001 are okay because the result from rounding errors.
3. 0≤P(x)≤1 for every individual value of the random variable x (each probability value must be between 0 and 1 inclusive)

Question 6

STATS 5-2

Probability Histogram

Answer 6

• horizontal axis: random variable

* vertical axis: probabilities

Question 7

STATS 5-2

Maximum usual value

Answer 7

μ + 2σ

mean + 2x standard deviation

Question 8

STATS 5-2

Minimum usual value

Answer 8

μ-2σ

population mean - 2x standard deviation