section 4.1: normal distribution

Question 1

what are the distinct features of the normal distribution?

Answer 1

• unimodal
• symmetric
• bell shaped curve

Question 2

how are normal distributions denoted?

Answer 2

N(μ, σ)

Question 3

what is σ in a normal distribution?

Answer 3

the standard deviation

Question 4

what is μ in a normal distribution?

Answer 4

the mean

Question 5

what is a z score?

Answer 5

the number of standard deviations it falls above or below the mean

Question 6

how is a z score calculated?

Answer 6

(observation - mean) / standard deviation

Question 7

when is an observation considered unusual?

Answer 7

when it falls more then 2 standard deviations away from the mean

Question 8

what is a percentile?

Answer 8

the percentage of observations that fall below a given data point

Question 9

how do we compute a percentile?

Answer 9

pnorm(observation, mean, standard deviation)

Question 10

every normal distribution has an area under the curve of ________

Answer 10

1

Question 11

what is the 68 - 95 - 99.7 rule?

Answer 11

68% of the data is within one standard deviation

95% of the data is within two standard deviations

99.7% of the data is within three standard deviations