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AP Stats > Unit Quiz 2 > Flashcards

Unit Quiz 2 Flashcards

1
Q

Rules for density curve

A

Area under the curve is one
always on or above the X axis is horizontal
it is the overall pattern of distribution

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2
Q

Facts about normal distributions

A

bell shaped
Roughly symmetric
Unimodal
Npp will be linear

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3
Q

If the distribution has a constant added or subtracted to it what is the effect on the distribution

A

The center changes by the constant is added or subtracted by the constant
there is no effects to the shape
there is no effects to the spread

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4
Q

If the distribution is multiplied or divided by constant what happens to the distribution

A

The center is multiplied or divided by the constant there’s no effect to the shape
the spread is multiplied or divided by that constant

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5
Q

Mean is greater than median

A

Right skewed

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6
Q

mean less than median

A

Left skewed

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7
Q

Right skewed

A

Mean is greater than median

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8
Q

Left skewed

A

Mean is less than median

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9
Q

Percentages for normal distribution

A

68, 95, 99.7 … 100

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10
Q

Formula to find a score

A

Number of observations minus mean all over standard deviation

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11
Q

Finding area to the left(less than the value)

A

Table A of that value

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12
Q

Finding area to the right(more than the value)

A

1- table A of that value

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13
Q

Area between(between 2 values)

A

Bigger table A(value more to the right) minus smaller table A(value more to the left)

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14
Q

Given area find Z

A

Look I’m center of table A and look outwards to column and rows to identify z score

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15
Q

What does proportions means

A

U should standardize(use z score)

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16
Q

when do you use z score vs percentages

A

Z score when comparing, or proportions or even possibly finding the percentage

17
Q

the path percentile of a distribution is the value with

A

p percent of observations less than it

18
Q

What is a cumulative relative frequency graph used for

A

It is used to determine the position of an individual within a distribution or to locate a specified percentile of the distribution

19
Q

What value should the fuck you want to frequency be? (percent wise)

A

1 or 100%

20
Q

How is the z score interpreted in analysis or questions when u have to explain (for ex,pale the z -score is -0.51)

A

This observation was .59 SDU(standard deviation units) below the mean

21
Q

Can u subtract z scores then find the area?

A

NO always use stable A first then subtract!
Remember z scores are just proportions!

22
Q

What is the order when trying to find the area “between” and starting with the observations

A

First find z score then find area in Table A then subtract!

23
Q

How to find normal distribution problem

A
  1. State the distribution that is of interest
  2. draw a normal curve with area shaded mean SDV in boundary lines
  3. Calculate do one of the following
    either compute z score and table A to find area or use calculator and write down the common normal cdf
24
Q

Steps for assessing normality problems

A
  1. graph it!
    dot plot, histogram, see if it is symmetric or bell -shaped
  2. Check the 68-95-99.7 rule
    count the number of observations w/in 3 SDV negative and positive from the mean. Does the data follow?
  3. Make a NPP with your calc
25
Q

How to make a NPP(normal probability plot) w calc

A

2nd
Stat plot
1
On
Type NPP
Data list
L1
Axis X
Graph
Zoom
a(zoom stat)

26
Q

How to center a graph?

A

Zoom 9

27
Q

If trying to find ig Barack was unusually young when I agua rated look at

A

Cumulative frequency graph

28
Q

Z score formula

A

Observation - mean / SDV

29
Q

If u standardize all observations in a data set

A

Mean becomes 0 and SDV a becomes 1

30
Q

If 6 houses sold for more and the total is 35 what does that mean

A

2 scored at or below so to find percentile it would be 29/35

31
Q

What to use for center when data is skewed

A

Median

32
Q

When using cumulative rel freq charts

A

Find median and IQR by look at decimal/percents on y axis

33
Q

What are the 3 factors in a standard deviation problem

A

Center
Shape
Spread

34
Q

0 z score = what percentile

A

50th

AP Stats (5 decks)

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