Psych 211: Chapter 6

A particular portion of the graph corresponds to a particular probability in the ________________________

population

z- scores are both negative and positive, but probabilities are always what?

positive

what does probability usually involved when having to do with frequency distributions?

probability usually involves populations of scores that can be displayed in a frequency distribution graph.

the proportions of area apply to any normal distribution regardless of what to things?

regardless of the mean and regardless of the standard deviation

when can unit normal table ONLY be used?

with normal-shape distributions

if you know the proportions, you can use the table to find the specific ________

z-score

Which of the following accurately describes the proportions in the tails of a normal distribution?

A. Proportions in the right-hand tail are greater than 0.50, and proportions in the left-hand tail are less than 0.50. B. Proportions in the right-hand tail are less than 0.50, and proportions in the left-hand tail are greater than 0.50. C. Proportions in both tails are less than 0.50. D. Proportions in both tails are greater than 0.50. Answer: C (proportions in both tails are less than 0.50)

what proportion of a normal distribution is located in the tail beyond z= 1.50?

A. 0.9332 B. 0.0668 C. 0.4332 D. 0.1336 Answer: B (0.0668)

A class consists of 10 males and 30 females. If one student is randomly selected from the class, what is the probability of selecting a male?

A. 10/30 B. 10/40 C. 1/10 D. 1/40 Answer: B (10/40)

which of the following is a requirement for a random sample?

A. Every individual has an equal chance of being selected. B. The probabilities cannot change during a series of selections. C. There must be sampling with replacement. D. All of the other 3 choices are correct. Answer: D (all of the other 3 choices are correct

what are the 2 things needed for a random sample?

- each individual in the population has an equal chance of being selected - probabilities must stay constant from one selection to the next, if more than one individual is selected

what are the characteristics of a normal distribution?

- its a common shape - symmetrical - highest frequency in the middle - frequency tapers off towards the extremes

Which of the following accurately describes the proportions of the nails of a normal distribution

A. Proportions in the right-hand tail are positive, and proportions in the left-hand tail are negative. B. Proportions in the right-hand tail are negative, and proportions in the left-hand tail are positive. C. Proportions in both tails are positive. D. Proportions in both tails are negative. Answer: C (proportions in both tails are positive)

which of the following is a trait of a normal distribution?

A. Sections on the left side of the distribution have the same area as corresponding sections on the right B. Because z-scores define the sections, the proportions apply to any normal distribution C. z- scores have nothing to do with it D. both A and B

the proportions on the right side always _________ to proportions on the left side

equal

true or false: body plus tail always equals 2

false; always equals 1

the unit normal table lists relationships between z-score ______ and proportions in a ___________ ___________

locations; normal distribution

In the unit normal table what is the larger section called?

the body

in the unit normal table what is the smaller section called?

the tail

what do different portions of the graph represent?

they represent portions of the population

true or false: if you know the z-score, you can look up the corresponding proportion

true

true or false: proportions and probabilities are equivalent

true

true or false: z- scores are used to identify sections

true