Deductive Reasoning

Using the Law of Syllogism, which of the following completes the statement to form a valid conclusion?
If it is snowing heavily, then school will be canceled.
If school is canceled, the big test will not be given today.
It is snowing heavily, then...

• Look out for the snowplows while driving to school.
• The big test will not be given today.
• The roads will be hard to drive on.
• You should call the school to see if school is canceled.

Using the statements:
If it is Friday, then I will get paid.
It is Friday.
Write the conclusion.

• It is not Friday
• It is Friday
• I will not get paid
• I will get paid

Tags

CCSS.HSS.CP.A.3

CCSS.HSS.CP.B.6

Which is a valid conclusion from these statements?
If a quadrilateral is a rhombus, then it is a parallelogram.
If a quadrilateral is a parallelogram, then its opposite angles are congruent.

• Opposite angles of a quadrilateral are congruent
• Opposite angles of a rhombus are congruent
• Every quadrilateral is a rhombus
• Every parallelogram is a rhombus

Tags

CCSS.HSG.CO.C.11

Which statement is a valid conclusion based on the argument?
If a polygon is a regular pentagon, then the polygon has exactly five congruent angles.
The polygon is a regular pentagon.

• Therefore, the polygon is a rectangle.
• Therefore, the polygon is a regular quadrilateral.
• Therefore, the polygon has exactly five congruent angles.
• Therefore, the polygon has congruent sides.

Tags

CCSS.HSG.CO.C.11

p→q
q→r
∴p→r
Which law is modeled?

• Law of Syllogism
• Law of Detachment
• Law of Contrapositive
• Law of Shannon

p→q
p
∴q
Which law is modeled?

• Law of Syllogism
• Law of Detachment
• Law of Contrapositive
• Law of Shannon

(1) If you have a can opener, you can open a can.
(2) Jon has a can opener.
(3) John can open a can.
Is statement (3) logical given the Law of Detachment, Syllogism, Contrapositive, or is it invalid?

• Law of Syllogism
• Law of Detachment
• invalid

If a mineral is gypsum, it has a hardness of 2.
If a mineral has a hardness of 2, it can be scratched with a fingernail.
Using the Law of Syllogism, what logically comes next?

• If a mineral can be scratched with a fingernail, then it is gypsum.
• If a mineral is gypsum, it can be scratched with a fingernail.
• If a mineral has a hardness of 2, then it can't be scratched with anything.
• It can be scratched with a fingernail.

If an angle is 40⁰, then it is acute.
∠A is 40⁰.
Using the Law of Detachment, what is the logical statement to conclude?

• ∠A is complementary to ∠B
• ∠A is acute.
• ∠A is obtuse.
• ∠A is 40⁰

Tags

CCSS.HSG.CO.A.1

(1)  If it is a rabbit, then it has long ears.
(2)  Peter Cottontail has long ears.
(3)  Peter Cottontail is a rabbit.
Is statement (3) logical given the Law of Detachment, Syllogism, Contrapositive, or is it invalid?

• Law of Syllogism
• Law of Detachment
• Law of Contrapositive
• invalid