Normal Distribution Curves and Z-scores

Normal Distribution Curves and Z-scores

Fill in the Blanks

Normal Distribution Curves are based on a few variables, such as, the ___________, the________, and the ________________.

Multiple Choice

Most Normal Distribution Curves look like:

• a mole hill

• a sin wave

• a bell curve

• a parabola

Multiple Select

What are the kind of skewed bell curves in Normal Distribution?

• skewed left

• skewed right

• symmetrically skewed

• under skewed

• over skewed

Multiple Choice

What does skewed left mean?

• The values of the population are lower than the average for the survey sample meaning the average is left of the central peak

• The values of the population are higher than the average for the survey sample meaning the average is to the right of the central peak

Multiple Choice

What does skewed right mean?

• The values of the population are lower than the average for the survey sample meaning the average is left of the central peak

• The values of the population are higher than the average for the survey sample meaning the average is to the right of the central peak

Fill in the Blanks

A Z-score is describes the position of a _________ in terms of its distance from the_____ when measured in _________ units.

Multiple Choice

The  Z-score formula is

 $\left(X-\mu\right)\div\sigma$  

•  $\left(X-\mu\right)\div\sigma$  

•  $\left(X+\mu\right)\div\sigma$  

•  $\left(X-\mu\right)\times\sigma$  

Multiple Select

The X in the Zscore formula is for

• cluster sample from questionnaire

• total pop sample observed in experiment

• observed value in survey

• professor xavier

Multiple Choice

 $\mu$  in the Z-score formula is for 

• the IQR of the data range 

• average of the sample

• the standard deviation of the sample

• the variance of the sample

Multiple Choice

 $\sigma$  in the Z-score formula is for 

• the median of the sample

• the mean of the sample

• the standard deviation of the sample

• The mode of the data sample

Multiple Choice

z-scores can not be negative

• true

• false

Multiple Choice

A positive Z-score means the final value was greater than the mean used in the data sample

• true

• false

Multiple Choice

 $\mu$  

In a bell curve, where the average is the center column, what is the percentage if we take a sample only 1 standard deviation away?

• 68%

• 95%

• 99.7%

• 3.2%

• 32%

Multiple Choice

When a problem asks to calculate the area under the bell curve signifying a level that is below the mean, do we take asymmetrical measurements to the left?

• yes

• no

Multiple Choice

When a problem asks to calculate the area under the bell curve signifying a level that is above the mean, do we take asymmetrical measurements to the right?

• yes

• no