Inductive and Deductive Reasoning

Mental Drill: Identify the missing figure.

A

B

C

D

Mental Drill: Identify the missing figure.

A

B

C

D

Mental Drill: Identify the missing figure.

A

B

C

D

Mental Drill: Identify the missing figure.

A

B

C

D

Mental Drill: Identify the missing figure.

A

B

C

D

Open Ended

1) Jason often comes to school late. His class starts at 7:30AM, so he wakes up at 6AM and leaves the house at 7AM for the 30 minute commute to school. Still he comes in late due to the unpredictable traffic situation. One day, he wakes up at 5:30AM, leaves the house at 6:30AM and is in school at 7:00AM. He does this for several days and gets the same result. What can he conclude?

Open Ended

2 ) Write a conjecture that is based on the given information.

     Given:

  Tilapia and Bangus are fish and they can swim.

  Tuna and Salmon are fish and they can swim.

  Sharks are fish and they can swim.

Counterexample

An easy way to disprove a conjecture is to give a counterexample, that is,

an example that shows the statement to be false.

Example:

Premise: Parrot is a bird, it can fly.

Premise: Hawk is a bird, it can fly.

Conclusion: All birds can fly.

Open Ended

Give a counterexample to show that the given conjecture is false.

Given:

Premise: 16 is an even number and it is divisible by 4.

Premise: 32 is an even number and it is divisible by 4.

Conclusion: If a number is even, it is divisible by 4.

Open Ended

Give a counterexample to show that the given conjecture is false.

Given:

Premise: The ordered pair (2,3) consists of non-negative coordinates and is located on Quadrant I.

Premise: The ordered pair (5,11) consists of non-negative coordinates and is located on Quadrant I.

Conclusion: All ordered pairs with non-negative coordinates are located on Quadrant I.

Open Ended

Write a conjecture that is based on the given information.

  1) A student who attains a perfect score in the first quiz will be given extra credit. Kim attained a perfect score in the first quiz.

Open Ended

Write a conjecture that is based on the given information.

        2) No foreigner can be elected as the president of our country.

            Jin is a foreigner. 

Open Ended

Write a conjecture that is based on the given information.

        2) No foreigner can be elected as the president of our country.

            Jin is a foreigner. 

Open Ended

Write a conjecture that is based on the given information.

3)   All the residents in Biñan, Laguna are exempted from paying

            taxes.

JK’s parents reside in Biñan, Laguna. 

Multiple Choice

Practice Exercise: Determine whether the reasoning used in the given argument is inductive or deductive.

A parallelogram has two pairs of parallel opposite sides.

      A rectangle is a parallelogram.

      Therefore, a rectangle has two pairs of parallel opposite sides.

• Deductive

• Inductive

Multiple Choice

Practice Exercise: Determine whether the reasoning used in the given argument is inductive or deductive.

All rectangles have four right angles.

  A square is a rectangle.

Therefore, a square has four right angles.

• Deductive

• Inductive

Multiple Choice

Practice Exercise: Determine whether the reasoning used in the given argument is inductive or deductive.

100 is divisible by 10 and its last digit is 0.

       250 is divisible by 10 and its last digit is 0.

       Therefore, if a number is divisible by 10 then its last digit is 0.

• Deductive

• Inductive