# Statistics and Probability

- Created by: examstressed1808
- Created on: 15-03-15 13:45

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- Maths revision: Statistics and Probability
- Compound Interest and Depreciation
- N = No (1+r/100)^n
- This means: Existing amount = Initial amount (1 + percentage change per day/hour/year) ^ number of days/hrs/yrs/

- N = No (1+r/100)^n
- Relative frequency
- Probability of something happening = no. of times it happened / no. of times you tried
- The more times you do the experiment, the more accurate the probability is

- Data
- Quantitative = quantities
- Qualitative = descriptive
- Discrete = recorded exactly
- Continuous = take any value in an interval

- Cumulative Frequency
- Means 'Adding it up as you go along'
- Shown in Box Plots

- Histograms
- Its not the height but the area of the bar that matters
- Frequency density = Frequency / Class-width

- Frequency Polygons
- Shows information from a frequency table
- A kind of line graph

- Finding the gradient of a straight line graph
- !) Find two accurate points a complete the triangle
- 2) Find the change in Y and the change in X
- Change in X = X coordinate of point a - X coordinate of point B
- Change in Y = Y coordinate of point A - Y coordinate of point B

- 3) Gradient = Change in Y / Change in X

- Compound Interest and Depreciation
- Sampling
- Maths revision: Statistics and Probability
- Compound Interest and Depreciation
- N = No (1+r/100)^n
- This means: Existing amount = Initial amount (1 + percentage change per day/hour/year) ^ number of days/hrs/yrs/

- N = No (1+r/100)^n
- Relative frequency
- Probability of something happening = no. of times it happened / no. of times you tried
- The more times you do the experiment, the more accurate the probability is

- Data
- Quantitative = quantities
- Qualitative = descriptive
- Discrete = recorded exactly
- Continuous = take any value in an interval

- Cumulative Frequency
- Means 'Adding it up as you go along'
- Shown in Box Plots

- Histograms
- Its not the height but the area of the bar that matters
- Frequency density = Frequency / Class-width

- Frequency Polygons
- Shows information from a frequency table
- A kind of line graph

- Finding the gradient of a straight line graph
- !) Find two accurate points a complete the triangle
- 2) Find the change in Y and the change in X
- Change in X = X coordinate of point a - X coordinate of point B
- Change in Y = Y coordinate of point A - Y coordinate of point B

- 3) Gradient = Change in Y / Change in X

- Compound Interest and Depreciation
- Stratified sampling = makes sure the proportion of people in each group is the same in the sample as it is in the whole population.
- Sample frame = list/map of all the members of the population
- Population = group you want to investigate

- Maths revision: Statistics and Probability
- Quartiles and interquartile range
- Quartiles divide data into four equal groups
- Lower quartile (Q1)
- Median (Q2)
- Upper quartile (Q3)

- To find Quartiles
- 1) Put the values in ASCENDING order
- 2) Work out the quartiles using the following formulas:
- Q1 = (n+1)/4
- Q2 = 2(n+1)/4
- Q3 = 3(n+1)/4

- 2) Work out the quartiles using the following formulas:

- 1) Put the values in ASCENDING order
- Interquartile = 'Between Quartiles'
- Interquartile range is the difference between the upper and lower quartile

- Quartiles divide data into four equal groups
- To find Quartiles
- 1) Put the values in ASCENDING order
- 2) Work out the quartiles using the following formulas:
- Q1 = (n+1)/4
- Q2 = 2(n+1)/4
- Q3 = 3(n+1)/4

- 2) Work out the quartiles using the following formulas:

- 1) Put the values in ASCENDING order
- Interquartile = 'Between Quartiles'
- Interquartile range is the difference between the upper and lower quartile

- Frequency Tables
- Mean is found using: 3rd Row total/2nd Row total
- Median found from middle value in 2nd row
- Range found from extremes of the first row

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