Probability

Question 1

What are all of the set notations for Venn diagrams?

Answer 1

a = everything in the circle a including the middle bit
a’ = everything except the circle a. Outside of the Venn diagram also counts
a u b = all of a and b
a n b = the bit in the middle

Question 2

How do u draw a probability tree diagram? For independent events (doesn’t matter what happened before)

Answer 2

1. 2 or more branches
2. Write the name at the end of whats happening (eg. Red and blue)
3. Write the probability of it happening in either fractions or decimals along the branches
4. Do the same for the 2nd (and more) set of branches

Question 3

How to calculate probability along 2 branches?

Answer 3

Multiply them together
Eg. 3/7 * 3/7 = 6/49

Question 4

How to calculate probability along multiply branches together?

Answer 4

Multiply each probability and add them all together
Eg. (3/7 * 3/7) + (3/7 * 4/7) + (4/7 * 3/7) = 33/49

Question 5

How to draw a probability tree diagram for dependent events? (Probability depends on what u chose first)

Answer 5

1. 2 or more branches
2. Write the name at the end of whats happening (eg. Red and blue)
3. Write the probability of it happening in either fractions or decimals along the branches
4. For the 2nd set of branches, pretend that if they took a counter of a specific colour for example, remember to subtract your denominator so as there will only be 1 less than before as it has been taken out and not replaced, depending on what the first branch is, do the same for numerator
   Eg. 3/7 —> 2/6
5. Repeat as necessary

Question 6

What is the difference between frequency trees and probability diagram?
Eg. 20 counters total and 5 blue and 15 red

Answer 6

Frequency trees say the actual amount eg. 5 and 15
While probability diagrams say the decimal/percentage of how likely eg. 0.25 and 0.75