If…, then… – practice for Years 7–9
Sample questions on If…, then… with the right answer and a worked solution, from easy to hard. In the Pickles Academy app a child gets new questions of the same kind every time, so they can't just learn the answers by heart.
- Subject
- Logic
- Year
- Years 7–9
- Curriculum area
- Statements and truth
Question types: What follows?
Rule: If…, then…
From “if P, then Q” and P, Q follows. From “if P, then Q” and “not Q”, “not P” follows.
Not the other way round: Q does not give you P, and “not P” does not give you “not Q”.
Example: If it rains, the ground is wet. The ground is dry, so it is not raining. The ground is wet? Then we can’t tell.
Watch out: “If it rains, the ground is wet” does not mean “if the ground is wet, it is raining”. The reverse rule doesn’t hold.
Sample questions
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Question 1 Easy
The rule is: If it is Saturday, then Peter plays football. We know that it is Saturday. Decide whether each statement must follow (YES) or not (NO).
- Peter plays football.
- Peter does not play football.
- It is not Saturday.
Show the solution
Answer:- Peter plays football. – yes
- Peter does not play football. – no
- It is not Saturday. – no
How it works: 1. YES 2. NO 3. NO The rule also gives its contrapositive: if the second part is false, so is the first. The converse does not follow.
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Question 2 Normal
The rule is: If it is raining, then Eva has an umbrella. We know that it is raining. Decide whether each statement must follow (YES) or not (NO).
- Eva does not have an umbrella.
- It is not raining.
- Eva has an umbrella.
Show the solution
Answer:- Eva does not have an umbrella. – no
- It is not raining. – no
- Eva has an umbrella. – yes
How it works: 1. NO 2. NO 3. YES The rule also gives its contrapositive: if the second part is false, so is the first. The converse does not follow.
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Question 3 Hard
The rule is: If the number ends in 0, then the number is even. We know that the number is odd. Decide whether each statement must follow (YES) or not (NO).
- If the number is even, then the number ends in 0.
- If the number is odd, then the number does not end in 0.
- The number ends in 0.
- The number does not end in 0.
- The number is even.
Show the solution
Answer:- If the number is even, then the number ends in 0. – yes
- If the number is odd, then the number does not end in 0. – yes
- The number ends in 0. – no
- The number does not end in 0. – yes
- The number is even. – no
How it works: 1. YES 2. YES 3. NO 4. YES 5. NO The rule also gives its contrapositive: if the second part is false, so is the first. The converse does not follow.
Keep practising in the app
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