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Conditional probability from a tree diagram

Conditional probability from a tree diagram.

  • Identify the outcomes that are still possible after applying the condition.
  • Use the number or probability meeting both requirements in the numerator.
  • The denominator comes from the restricted sample space, not automatically the original total.

Example 1

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.

Example 2

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.

Your turn

Question 1

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Check answer
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.
Question 2

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Check answer
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.
Question 3

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Check answer
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.
Question 4

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Check answer
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.
Question 5

Use the tree to find .

Two-stage probability treeFirstSecondABB′A′BB′
Check answer
Multiply along the A then B route.Add both routes that end in B.Divide the intersection probability by the given-event probability.
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