Maths · OCR Paper 2
Probability
The probability skills tested on OCR Paper 1: relative frequency and expected outcomes, tree diagrams, Venn diagrams and set notation, frequency trees and two-way tables, and conditional probability.
Lessons
Ticks are remembered on this device only.
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1
Probability Basics and Relative Frequency
Calculating simple probabilities, using the probability scale, and estimating from relative frequency and expected outcomes.
9 terms -
2
Tree Diagrams
Combining independent and dependent events with tree diagrams, with and without replacement.
9 terms -
3
Venn Diagrams and Set Notation
Using sets, Venn diagrams and set notation to organise data and find probabilities.
9 terms -
4
Frequency Trees and Two-Way Tables
Completing frequency trees and two-way tables and using them to find probabilities.
9 terms -
5
Conditional Probability
Finding probabilities given that something has already happened, from tables, Venn diagrams and tree diagrams.
9 terms
Key terms in this chapter
All 45, gathered from every lesson.
- Probability
- A number from 0 to 1 that measures how likely an event is.
- Outcome
- One possible result of an experiment.
- Event
- One or more outcomes that you are interested in.
- Sample space
- A list or table of all the possible outcomes.
- Mutually exclusive
- Events that cannot happen at the same time.
- Relative frequency
- The fraction of trials in which an event happened.
- Expected frequency
- The number of times an event is expected to happen, found by probability times trials.
- Biased
- Not fair, with some outcomes more likely than others.
- Random
- Chosen so that every outcome has an equal chance.
- Tree diagram
- A diagram with branches that shows the outcomes of events in order and their probabilities.
- Branch
- A line on a tree diagram showing one possible outcome and its probability.
- Independent events
- Events where one does not affect the probability of the other.
- Dependent events
- Events where the first changes the probability of the second.
- Replacement
- Putting an item back before the next pick.
- Without replacement
- Not putting an item back, so the next pick has fewer items.
- At least one
- One or more, found as 1 minus the probability of none.
- Outcome probability
- The probability of one complete path through the tree.
- Product
- The result of multiplying.
- Set
- A collection of items, written in curly brackets.
- Universal set
- The set of everything being considered, written \(\xi\).
- Intersection
- The items in both sets, written \(A \cap B\).
- Union
- The items in either set or both, written \(A \cup B\).
- Complement
- The items not in a set, written \(A'\).
- Element
- A member of a set.
- Venn diagram
- A diagram with overlapping circles showing how sets overlap.
- Overlap
- The region where two circles intersect.
- Region
- One of the separate parts of a Venn diagram.
- Two-way table
- A table that shows how many items have each combination of two features.
- Frequency tree
- A tree diagram with the number of items on each branch.
- Frequency
- The number of times something happens or the number of items in a group.
- Row
- A horizontal line of cells in a table.
- Column
- A vertical line of cells in a table.
- Total
- The sum of a row, a column or the whole table.
- Grand total
- The total of everything in the table.
- Survey
- A set of questions asked to a group of people to collect data.
- Expected frequency
- The number of times you expect something to happen, found as probability times the number of trials.
- Conditional probability
- The probability of an event given that another event has happened.
- Given that
- The words that mean you only look at part of the group.
- Independent
- Events where knowing one has no effect on the probability of the other.
- Group
- The set of items you are choosing from, after any given information.
- Denominator
- The number on the bottom of a fraction.
- Tree diagram
- A diagram showing outcomes in stages with probabilities on branches.
- Two-way table
- A table of counts sorted by two features.
- Venn diagram
- A diagram of overlapping sets with the number in each region.
- Notation
- The symbols used in mathematics, such as \(P(A \mid B)\).