Statistics Chapter 6: Probability distributions

Question 1

random variable

Answer 1

numerical measurement of the outcome of a random phenomenon. Often, the randomness results from the use of a random sampling or a randomized experiment to gather data

Question 2

probability distribution

Answer 2

possible values of a random variable and their probabilities

Question 3

discrete random variable

Answer 3

probability distribution:

• for each x, the probability P(x) falls between 0 and 1
• sum of the probabilities for all the possible x values equals 1

Question 4

continuous random variable

Answer 4

probability distribution:

• each interval has the probability between 0 and 1
• the interval containing all possible values ha probability equal to 1, so the total area under the curve equals 1

Question 5

normal ditribution

Answer 5

symmetric, bell-shaped, and characterized by its mean mu and standard deviation sigma (1 sd: 68%, 2 sd: 95%, 3 sd: 99,7%)

Question 6

z-score

Answer 6

number of standard deviations that x falls from the mean

z=x-mean/standard deviation (x=mean+z*standard deviation)

Question 7

standard normal distribution

Answer 7

normal ditribution with mean 0 and standard deviation 1