Items 1315 Circle the type of reasoning used Circle Invalid

Items 13-15: Circle the type of reasoning used. Circle \"Invalid\" if the conclusion is not true.

13. David knows he is shorter than Jennifer.
David also knows that Cory is shorter than Jennifer.
David also reasons that he is taller than Cory.

114. Cory is told that Jennifer goes to the mall if and only if she finishes her chores.
He also knows that Jennifer was at the mall.
Cory reasons that Jennifer finished her chores.

15. After David finishes his homework, he usually plays video games.
David did not play video games on Wednesday.
Therefore David did not finish his homework on Wednesday.

Please explain how you got your answer, if you can.

Items 13-15: Circle the type of reasoning used. Circle \"Invalid\" if the conclusion is not true. David he is monter than eanur David also knows that Cory is shorter than Jennifer reasons that he is taller than Cory. Inductive Deductive Invalid 14. Cory is told that Jennifer goes to the mall if and only if she finishes her chores He also knows that Jennifer was at the mall. Cory reasons that Jennifer finished her chores. Inductive Deductive Invalid 15. After David finishes his homework, he usually plays video games. David did not play video games on Wednesday Therefore David did not finish his homework on Wednesday. Inductive Deductive Invalid AMERICAN SCHOOL Lansing, IL

Solution

13.

David < Jennifer
Cory< Jennifer.

Lets Jennifer is 190 cm tall.
David and Cory are less than 190cm tall

David says he\' taller than Cory.

The answer is INVALID.

David can\'t make that statement, as he can be 180 and Cory can be 185cm.
Since the only given fact is that both\' heights are less than Cory\'