Practice worksheet on logical reasoning using the Law of Detachment and Law of Syllogism.
A practice worksheet titled "2-4 Practice" from Form K, featuring logic problems involving the Law of Detachment and Law of Syllogism, with statements about road tests, angles, swimming, theater attendance, triangles, divisibility, animals, languages, and angles.
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Show Answer Key & Explanations
Step-by-step solution for: SOLUTION: The law of syllogism - Studypool
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Show Answer Key & Explanations
Step-by-step solution for: SOLUTION: The law of syllogism - Studypool
Let's solve each problem step by step using logical reasoning, specifically the Law of Detachment and the Law of Syllogism.
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- Law of Detachment:
If we have:
- *If P, then Q.*
- *P is true.*
→ Then we can conclude: Q is true.
- Law of Syllogism:
If we have:
- *If P, then Q.*
- *If Q, then R.*
→ Then we can conclude: If P, then R.
Now let’s go through each question.
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#### 1.
> If you pass a road test, you will get your driver's license.
> Tamara passed her road test.
- Conditional statement:
If pass road test → get license
- Given fact: Tamara passed the road test → matches the hypothesis.
✔ Conclusion (by Law of Detachment):
Tamara will get her driver's license.
---
#### 2.
> If an angle is a right angle, then it is not acute.
> $ m\angle Q \neq 90 $
- Conditional: If right angle → not acute
- Given: $ m\angle Q \neq 90 $ → means ∠Q is not a right angle
But the hypothesis ("if it is a right angle") is not true, so we cannot apply the Law of Detachment.
✘ No conclusion possible.
We only know that ∠Q ≠ 90°, but that doesn’t tell us whether it's acute or not. It could be obtuse or acute — no definite conclusion.
---
#### 3.
> If you swim 100 m in less than 90 seconds, you will be on the swim team.
> Jeremy swam 200 m in 190 s.
- Hypothesis: "swim 100 m in <90 sec" → must be true to trigger conclusion.
- But Jeremy swam 200 m in 190 s → his time for 100 m would be about 95 s (190 ÷ 2), which is more than 90 s.
So he did not meet the condition.
✘ No conclusion possible.
We don't know if he qualifies for the team based on this information.
---
#### 4.
> If you arrive at the theater by 2:00 p.m., you can see the show.
> Julie arrived at 1:45 p.m.
- Hypothesis: arrive by 2:00 p.m. → she did (1:45 < 2:00)
✔ So by Law of Detachment:
Julie can see the show.
---
#### 5.
> If a triangle has one obtuse angle, then it is an obtuse triangle.
> △ABC has an acute angle.
- Conditional: If has one obtuse angle → obtuse triangle
- Given: △ABC has an acute angle → this does not match the hypothesis
We don't know if it has an obtuse angle. A triangle can have acute angles and still be acute, right, or obtuse.
✘ No conclusion possible.
The given fact does not satisfy the hypothesis.
---
#### 6.
> If the sum of the digits in a number is 9, then the number is divisible by 9.
> If a number is divisible by 9, then it is divisible by 3.
- First: If sum of digits = 9 → divisible by 9
- Second: If divisible by 9 → divisible by 3
→ The conclusion of the first (divisible by 9) matches the hypothesis of the second.
✔ Apply Law of Syllogism:
If sum of digits = 9 → divisible by 3
So, final conclusion:
If the sum of the digits in a number is 9, then the number is divisible by 3.
---
#### 7.
> If an animal has hair, it is a mammal.
> If an animal gives birth to live young, it is a mammal.
- First: If has hair → mammal
- Second: If gives live birth → mammal
But the conclusion of the first (mammal) is not the hypothesis of the second (live birth).
They both lead to the same conclusion, but are not linked in a chain.
✘ No conclusion possible via Law of Syllogism.
There is no common link between the two statements' hypotheses and conclusions.
---
#### 8.
> If a language is Spanish, it is a Romance language.
> If a language is a Romance language, it has Latin roots.
- First: If Spanish → Romance language
- Second: If Romance language → has Latin roots
→ Conclusion of first (Romance) matches hypothesis of second.
✔ Apply Law of Syllogism:
If a language is Spanish, then it has Latin roots.
---
#### 9.
> If two angle measures sum to 180, then the angles are supplementary.
> If two angle measures sum to 90, then the angles are complementary.
- First: sum = 180 → supplementary
- Second: sum = 90 → complementary
These are two separate conditions with different sums.
There is no logical connection between them (one is about 180, the other about 90).
✘ No conclusion possible.
The conclusion of one does not match the hypothesis of the other.
---
#### Using Law of Detachment:
1. Yes: Tamara will get her driver's license.
2. No: $ m\angle Q \neq 90 $ does not confirm it's a right angle.
3. No: Jeremy didn't swim 100 m in under 90 s.
4. Yes: Julie can see the show.
5. No: Having an acute angle doesn't imply it has an obtuse angle.
#### Using Law of Syllogism:
6. Yes: If sum of digits is 9, then the number is divisible by 3.
7. No: No common link between the statements.
8. Yes: If a language is Spanish, then it has Latin roots.
9. No: The statements are unrelated (different sums).
---
Let me know if you'd like these written in a table format!
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🔹 Recall:
- Law of Detachment:
If we have:
- *If P, then Q.*
- *P is true.*
→ Then we can conclude: Q is true.
- Law of Syllogism:
If we have:
- *If P, then Q.*
- *If Q, then R.*
→ Then we can conclude: If P, then R.
Now let’s go through each question.
---
✔ Part 1: Use Law of Detachment
#### 1.
> If you pass a road test, you will get your driver's license.
> Tamara passed her road test.
- Conditional statement:
If pass road test → get license
- Given fact: Tamara passed the road test → matches the hypothesis.
✔ Conclusion (by Law of Detachment):
Tamara will get her driver's license.
---
#### 2.
> If an angle is a right angle, then it is not acute.
> $ m\angle Q \neq 90 $
- Conditional: If right angle → not acute
- Given: $ m\angle Q \neq 90 $ → means ∠Q is not a right angle
But the hypothesis ("if it is a right angle") is not true, so we cannot apply the Law of Detachment.
✘ No conclusion possible.
We only know that ∠Q ≠ 90°, but that doesn’t tell us whether it's acute or not. It could be obtuse or acute — no definite conclusion.
---
#### 3.
> If you swim 100 m in less than 90 seconds, you will be on the swim team.
> Jeremy swam 200 m in 190 s.
- Hypothesis: "swim 100 m in <90 sec" → must be true to trigger conclusion.
- But Jeremy swam 200 m in 190 s → his time for 100 m would be about 95 s (190 ÷ 2), which is more than 90 s.
So he did not meet the condition.
✘ No conclusion possible.
We don't know if he qualifies for the team based on this information.
---
#### 4.
> If you arrive at the theater by 2:00 p.m., you can see the show.
> Julie arrived at 1:45 p.m.
- Hypothesis: arrive by 2:00 p.m. → she did (1:45 < 2:00)
✔ So by Law of Detachment:
Julie can see the show.
---
#### 5.
> If a triangle has one obtuse angle, then it is an obtuse triangle.
> △ABC has an acute angle.
- Conditional: If has one obtuse angle → obtuse triangle
- Given: △ABC has an acute angle → this does not match the hypothesis
We don't know if it has an obtuse angle. A triangle can have acute angles and still be acute, right, or obtuse.
✘ No conclusion possible.
The given fact does not satisfy the hypothesis.
---
✔ Part 2: Use Law of Syllogism
#### 6.
> If the sum of the digits in a number is 9, then the number is divisible by 9.
> If a number is divisible by 9, then it is divisible by 3.
- First: If sum of digits = 9 → divisible by 9
- Second: If divisible by 9 → divisible by 3
→ The conclusion of the first (divisible by 9) matches the hypothesis of the second.
✔ Apply Law of Syllogism:
If sum of digits = 9 → divisible by 3
So, final conclusion:
If the sum of the digits in a number is 9, then the number is divisible by 3.
---
#### 7.
> If an animal has hair, it is a mammal.
> If an animal gives birth to live young, it is a mammal.
- First: If has hair → mammal
- Second: If gives live birth → mammal
But the conclusion of the first (mammal) is not the hypothesis of the second (live birth).
They both lead to the same conclusion, but are not linked in a chain.
✘ No conclusion possible via Law of Syllogism.
There is no common link between the two statements' hypotheses and conclusions.
---
#### 8.
> If a language is Spanish, it is a Romance language.
> If a language is a Romance language, it has Latin roots.
- First: If Spanish → Romance language
- Second: If Romance language → has Latin roots
→ Conclusion of first (Romance) matches hypothesis of second.
✔ Apply Law of Syllogism:
If a language is Spanish, then it has Latin roots.
---
#### 9.
> If two angle measures sum to 180, then the angles are supplementary.
> If two angle measures sum to 90, then the angles are complementary.
- First: sum = 180 → supplementary
- Second: sum = 90 → complementary
These are two separate conditions with different sums.
There is no logical connection between them (one is about 180, the other about 90).
✘ No conclusion possible.
The conclusion of one does not match the hypothesis of the other.
---
✔ Final Answers:
#### Using Law of Detachment:
1. Yes: Tamara will get her driver's license.
2. No: $ m\angle Q \neq 90 $ does not confirm it's a right angle.
3. No: Jeremy didn't swim 100 m in under 90 s.
4. Yes: Julie can see the show.
5. No: Having an acute angle doesn't imply it has an obtuse angle.
#### Using Law of Syllogism:
6. Yes: If sum of digits is 9, then the number is divisible by 3.
7. No: No common link between the statements.
8. Yes: If a language is Spanish, then it has Latin roots.
9. No: The statements are unrelated (different sums).
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Let me know if you'd like these written in a table format!
Parent Tip: Review the logic above to help your child master the concept of law of detachment worksheet.