# Statistics: Arithmetic Mean and Relative Frequency

**Topics:**Arithmetic mean, Standard deviation, Mean

**Pages:**7 (1088 words)

**Published:**September 18, 2013

CH1

In an observational study, researchers simply observe characteristics and take measurements, as in a sample survey.

In a designed experiment, researchers impose treatments and controls and then observe characteristics and take measurements.

Data from a sample of citizens of a certain country yielded the following estimates of average TV viewing time per month for all the citizens. Answer: Inferential, because the statistics are used to make inference about the population.

* 50 kids are divided into 2 groups. One is exposed to a vid on bullying. The other isn’t. After one week, both groups are questioned about their attitudes about violence. This is a designed experiment

5 state officials: Governor (G) , Secretary of State (S), Attorney (A), Representative ®, Press (P) a) list 10 possible samples w/out replacement of size 2

b) if a simple random sampling procedure is used to obtain a sample of two officials, what are the chances it’s the first sample?

GS, GA, GR, GP, SA, SR, SP, AR, AP, RP

1/10

CH 2

1. According to a technology company, 5 countries cost in a certain area. Identify type of data: Rank| Country| Cost|

1| Country a | $54|

2| Country b| $332|

3| Country c| $99|

4| Country d| $98|

5| Country e| $221|

Answer:

Rank: Quantitative, Discrete

Country: Qualitative

Cost: Quantitative, Continuous

2. original data is data about order or rank given on a scale such as 1, 2, 3.. or A, B, C,… does the following variable yield ordinal data?

Hair color

No, because the data isn’t ordered in some way

3. For a study, a student bought 3 bags of colored candy from stores and counted each color. The average number of each color in the three bags was distributed as shown.

Color| Frequency|

Brown| 556|

Yellow| 118|

Red| 344|

Orange| 57|

Green| 87|

Blue| 34|

a) obtain a relative – frequency distribution

College| Frequency| Relative frequency|

Brown | 157| .296|

Yellow| 118| .223|

red| 102| .192|

orange| 57| .108|

green| 48| .091|

blue| 48| .091|

a) RF = FN/(F1 + F2 + F3 + …. )

b) identify pie chart ( has same percentages as relative freq) c) bar chart ( not connected height matched relative freq.)

4. Questionaire with score results:

37| 15| 44| 24| 16|

22| 46| 53| 12| 52|

31| 35| 43| 18| 53|

38| 30| 44| 45| 46|

21| 17| 44| 37| 35|

a) determine frequency distribution:

Anxiety | Frequency|

12-18| 5|

19-25| 3|

26-32| 2|

33-39| 5|

40-46| 7|

47-53| 3|

Grouping is given by one, group the others like above. Then CAREFULLY tally them for the right column

b) obtain relative frequency:

Anxiety | Relative Frequency|

12-18| .2|

19-25| .12|

26-32| .08|

33-39| .2|

40-46| .28|

47-53| .12|

RF = FN / (F1+ F2 +F3…)

c) frequency histogram (connected, highest point number for frequency) d) rel freq. histogram (connected, highest point number for rel. frequency)

5. average height:

29.5 28.4 29.1 27.2 a) stem + leaf 27 2 30.1 30.1 29.4 28.4 28 3 4

29 1 2 5

30 1 1

B) stem + leaf (two lines per stem)

272

283 4

291 2

295

3011

(all numbers 0-4 on one line, 5-9 on another)

6/7. know shapes of distribution and the skews

8. know shapes of distribution, plot the stem and leaf graph

CH3

1. a) find the mean and median

c) replace one number with a higher number and find the mean and median again (mean changes, median stays the same)

d) which center of measure works better?

The median

2. four cars cost $....

a) find the mean of the cost ( add all and divide by number of things) b) find the median --- MAKE SURE YOU...

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