Week of March 4 (2019):
3 types of fruit, apples, peaches and oranges, are on a kitchen table. Each family member only likes one type of fruit.
Daddy doesn't like oranges.
Granny doesn't like oranges or apples.
What is William's favourite fruit?
Week of Feb. 4 (2019):
Heather spent $4 on a storybook.
She used half of the remaining money to buy 6 apples.
She was left with $4 after buying a hair clip that cost $2.
How much did Heather have to start with?
Solution:
The trick to this question is reading the sentences carefully. In essence we start with not knowing how much money Heather has, so we can call that amount x. First she spends $4 in a bookstore: x-4. We don't know how much is left, but we do know that she used half to by apples and the other half to buy a $2 clip leaving her with $4. If she had $4 at the end and spent $2, then one of the halves must have been $6. (2+4=6). If one half of the remaining money was $6, then it is safe to conclude that the other half is also $6 (equal amounts.) Now if the two halves are added together then (6+6=12), Heather had $12 left after she spent $4 in a bookstore. That then gives us $16 originally (12+4 = 16.)
Week of Jan 21 - 25 (2019):
A number is first subtracted by 8.
The difference is then multiplied by 8.
The product is then divided by 8.
The final result is still 8.
What is the number?
Solution:
The easiest way to find the solution is to start from the back. If we know that a certain number divided by 8 is 8, then we know that that number must be 64. If something multiplied by 8 will give you 64, then we know the number must be 8. Finally, if a number minus 8 is equal to 8, then the original number must have been 16.
Week of Jan 7 - 18 (2019):
Stephen, Xavier and Max each draw 2 cards from 7 cards that are numbered 2, 4, 6, 8, 10, 12, and 14.
Stephen: The sum of the numbers on my cards is 22.
Xavier: The sum of the numbers on my cards is 10.
Max: The sum of the numbers on my cards is 14.
Which card is left behind?
Stephen picked up - 8 and 14 = 22
Xavier picked up - 4 and 6 = 10
Max picked up - 2, 12 = 14
The card that was left behind is card 10.
Weeks of Oct 15-26:
In how many ways can you split 15 pompoms into 4 groups? Each group must have a different number of pompoms.
Solution:
Here are the options for grouping the 15 pompoms into 4 different groups. 1, 2, 3, 9
1, 2, 4, 8
1, 2, 5, 7
1, 3, 4, 7
1, 3, 5, 6
2, 3, 4, 6
Therefore, there are 6 different ways to group them so that the numbers in each group never repeat.
Week of Oct 8-12:
Again, please do not google the answer :)
Week of Oct 1 - 5:
A soccer ball flew right onto Mme. Kiss' back. 3 suspected culprits were called into the principal's office for investigation.
Shawn: "I did not do it!"
Andy: "Not me! But I saw Shawn kick that shot."
James: "Andy lied."
One of them told the truth. Who kicked the soccer ball?
If Shawn did it, then:
Shawn is lying, Andy is telling the truth and James is lying
If Andy did it, then:
Shawn is telling the truth, Andy is lying, and James is telling the truth
If James did it, then:
Shawn is telling the truth, Andy is lying and James is telling the truth.
The only solution where only one told the truth is when Shawn kicked the ball. Therefore, Shawn did it. The key piece of information in this question is that one person told the truth.
Week of Sept 24 - 28:
Paul is taller than Joe.
William is shorter than Paul.
Eddie is taller than William but shorter than Joe.
Rank all the children from the tallest to the shortest.
Solution:
The easiest way to solve this riddle is to start by figuring out the two extremes (tallest and shortest). The rest fall into place.
- Paul is taller than Joe and William. We also know that Eddie is shorter than Joe so the tallest is Paul.
- William is shorter than Paul, shorter than Eddie and since Eddie is shorter than Joe then, William is the shortest.
- Since Eddie is shorter than Joe, then the order from tallest to shortest is: Paul, Joe, Eddie, William
Solution:
The easiest way to solve this riddle is to start by figuring out the two extremes (tallest and shortest). The rest fall into place.
- Paul is taller than Joe and William. We also know that Eddie is shorter than Joe so the tallest is Paul.
- William is shorter than Paul, shorter than Eddie and since Eddie is shorter than Joe then, William is the shortest.
- Since Eddie is shorter than Joe, then the order from tallest to shortest is: Paul, Joe, Eddie, William
Week of Sept 17 - 21:
There is a boat that can fit himself plus either the wolf, the goat, or the cabbage.
If the wolf and the goat are alone on one shore, the wolf will eat the goat. If the goat and the cabbage are alone on the shore, the goat will eat the cabbage.
How can the farmer bring the wolf, the goat, and the cabbage across the river?
(DO NOT GOOGLE THE ANSWER!!!!!!! :))
This was a bit more challenging but many students seem to have worked it out :).
The problem in this question is the goat. It seems to be getting itself into trouble whether it stays with the cabbage or with the wolf. However, it is fine with the farmer. Since we have two seats in the boat, the farmer has to take the goat on a few extra trips :)
1) Farmer takes the goat across the river and leaves him there - no cabbage and no wolf - no problem.
2) Farmer then can take either the cabbage or the wolf to the other side, BUT MUST take the goat back on his return trip. Now we have a wolf on one side and a cabbage on the other. The goat is in the boat with the farmer.
3) Farmer drops off the goat where he was initially and picks up whichever was left (cabbage or wolf) and takes it to the other side. The goat is all alone in the meantime.
4) Farmer goes back for the goat. Again, the wolf and cabbage are fine together.
Week of Sept 10 - 14:
Défi Mathématique:
La somme de deux nombres est 80.
La différence de ces deux nombres est 12.
Trouvez les deux nombres.
(English)
The sum of two numbers is 80.
The difference of these two numbers is 12.
Find the two numbers.
Solution:
The solution to this question can be found using trial and error and knowing our additions and subtractions. The alternative solution is a bit too complex for now, but we will be learning how to do that too. :)
a + b = 80
a - b = 12
This means that 'a' needs to be the bigger number. If 'a' is 13, then 13-1 = 12, but 13+1 not= 80. We need much bigger numbers then. 40+40 = 80 but 40-40 not= 12.
One option we now have, is that since we know that 12 is made up of 6 + 6, we could take our 40s and increase one by 6 and decrease the other one by 6. The difference is 12 and because we are increasing and decreasing by the same amount, the total remains the same, or 80.
Therefore, 46 + 34 = 80; 46-34 = 12.
