Finding Z-Scores, Standard Deviation, Mean and X

A study surveyed a random sample of 45 students in the high school and found a mean savings of 1800 dollars with a standard deviation of 150 dollars.

Use the normal distribution/empirical rule to estimate a 95% CONFIDENCE INTERVAL for the mean.

*Round to a WHOLE NUMBER

(​ (a)   ​ ,​ (b)   )

• 1755

• 1845

• 1793

• 18007

• 1650

• 1750

• 0.32

• 0.6255

• 0.3745

• 76.493

• 0.7052

Given the following scenario, choose the correct numerical value to represent each of the lines in the standard normal bell curve pictured. The lifespans of monkeys in a particular zoo are normally distributed. The average monkey lives 18.2 years; the standard deviation is 2.4 years. line A: ​ (a)   line B: ​ (b)   line C: ​ ​ (c)   line D: ​ ​ ​ (d)  

• 11

• 18.2-2(2.4)

• 18.2 - 2.4

• 18.2 +3(2.4)

• 23

• 18.2

• 20.6

• 38.8

• -15.8

Find the standard deviation of the given data set:

• z = 2.33

• z = 0.6875

• z = 1.16

• z = 2.05

What information does a z-score give us?

• Position of a data point within a distribution relative to the mean.

• The number of pieces of data within a distribution.

• The mean of a distribution.

• The standard deviation of a distribution.

Which set of z-scores is always considered unusual?

Which z-scores are considered unusual? Check ALL that apply.

• z = 2.7

• z = 1.8

• z = -2.1

• z = 0

• z = -1.99

Calculate the z-score:
\mu=70
\sigma\ =\ 10
x\ =55

• z = -1.5

• z = 1.5

• z = 48

• z = 1.09

Approximately what percent of the data fall between two standard deviations of the mean?

• 68%

• 95%

• 99.7%

• Not enough information