Year 2 - Chapter 2 w/ Conditional Probability

Question 1

What is De’Morgans Law?

Answer 1

✯ (A ∩ B)’ = A’ ∪ B’

Question 2

Which method do we use for ∩ therefore?

Answer 2

✯ Method: Use the hash-tag method.

✯ Suppose we have A’ ∩ B. Shade in everything that is not A with vertical lines, and everything that is B with horizontal lines.

✯ The area, which has been shaded in with both vertical and horizontal lines (like a hash-tag) is the area of interest.

Question 3

What does ∩ mean?

Answer 3

✯ One of the three: Intersection, And, Overlap

Question 4

What does ∪ mean?

Answer 4

✯ One of the three: Union, Combined, Or

Question 5

Which method do we use for ∪ therefore?

Answer 5

✯ We combine the areas.

✯ Suppose we have A ∪ B, we will combine the shaded area of A and B for our desired area.

Question 6

What does P (A|B) mean?

Answer 6

✯ The probability of A occurring given that B has already occured.

Question 7

How can we calculate P (A|B)?

Answer 7

✯ P (A ∩ B) / P (B)

Question 8

If A and B are independent, how can we relate P (A|B) with P (A)?

Answer 8

✯ Suppose the two events A and B are independent, then
P (A| B) = P (A).

*given in formula booklet.