Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
4. Deductive Reasoning
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Exercise 34 Page 112

Practice makes perfect
a We have been given the following statements.
  • Statement I: Claire reads anything Andrea reads.
  • Statement II: Ben reads what Claire reads.
  • Statement III: Claire reads what Ben reads.
  • Statement IV: Andrea reads whatever Dion reads.
Let's write these statements as conditional and biconditional statements.
  • Statement I: If Andrea reads a book, then Claire reads the book.
  • Statement II: If Ben reads a book, then Claire reads the book.
  • Statement III: If Claire reads a book, then Ben reads the book.
  • Statement IV: If Dion reads a book, then Andrea reads the book,

We know that Claire is reading Hamlet, which matches the hypothesis of Statement III. Therefore, we can use the Law of Detachment to make a conclusion. If p → q &is true and p &is true, then q &is true. Let's apply the Law of Detachment. Conclusion Ben is reading Hamlet.

b Let's use the Law of Syllogism between Statement I and III, since the conclusion of Statement II matches the hypothesis of Statement III as the following.

If p → q &is true and q → r &is true, then p → r &is true. Applying the Law of Syllogism we have the following conclusion. Conclusion If Andrea reads a book, then Ben reads the book. As a result, we can say that If Andrea is reading King Lear, then Claire and Ben are also reading King Lear. However, we cannot make any comment about Dion's book.