Wednesday, May 17, 2023
(in North America and South America)
Thursday, May 18, 2023
(outside of North American and South America)
©2023 University of Waterloo
Half of 24 is
Answer: (D)
Reading from the graph, Friday had the highest temperature.
Answer: (C)
At a cost of $16.50 a basket, the cost to buy 4 baskets of
strawberries is
Answer: (B)
The difference between
Answer: (A)
Since
Further,
Thus, of the given answers, only 36 could be the result of multiplying
an integer by itself.
Alternatively, we may have noted that the result of multiplying an
integer by itself is a perfect square, and of the answers given, 36 is
the only perfect square.
Answer: (E)
Since the perimeter of
Each of the remaining three sides is equal in length, and so
Answer: (C)
Dividing 52 by each of the given denominators, we get that
Answer: (C)
The line segment with greatest length that joins two points on a
circle is a diameter of the circle. Since the circle has a radius of 4
cm, then its diameter has length
Answer: (B)
The number of integers in the list is 10. Of these integers, 5
are even (they are 10, 12, 14, 16, and 18). Thus, the probability that
the chosen integer is even is
Answer: (C)
Before adding tax, the combined cost of the three items is
The 5% tax on $15.00 is
Note that we could have calculated the 5% tax on each individual item,
however doing so is less efficient than calculating tax on the $15.00
total.
Answer: (D)
Since
Therefore,
Since the sum of the three angles in
Answer: (B)
Of the 100 small identical squares, 28 are presently unshaded,
and so
So that 75% of the area of
Therefore,
Answer: (A)
Suppose we call the unknown vertex
The side of the rectangle joining the points
This means that
Similarly, the side of the rectangle joining the points
This means that
Therefore, the coordinates of the fourth vertex of the rectangle are
Answer: (D)
The prime numbers that are less than 10 are
Thus, the only two different prime numbers whose sum is 10 are 3 and
7.
The product of these two numbers is
Answer: (D)
The given list,
The average of these 5 numbers is 6, and so the sum of the 5 numbers is
That is,
Answer: (D)
The sum of
The difference between
Since
The only numbers from 1 to 6 not accounted for are 4 and 5.
Since
Answer: (E)
Solution 1
The area of
Suppose the base of
Since
Thus, the area of
Solution 2
The area of
Suppose the base of
Since
Thus, the area of
The area of
Thus, the area of
Answer: (C)
The water is in the shape of a rectangular prism with a 2 cm by 5
cm base and depth 6 cm.
Therefore, the volume of water is
A face of the prism having the greatest area has dimensions 5 cm by 8
cm.
When the prism is tipped so that it stands on a 5 cm by 8 cm face, the
water is once again in the shape of a rectangular prism with a 5 cm by 8
cm base and unknown depth.
Suppose that after the prism is tipped, the water’s depth is
Since the volume of water is still
When the prism is tipped so that it stands on a face with the greatest
area, the depth of the water is
Answer: (D)
Solution 1
We begin by completing a table in which the ones digit of each
possible product is listed.
For example, when the number on the first die is 3 and the number on the
second die is 6, the entry in the table is 8 since
Number on the second die | |||||||
---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | ||
Number on the First Die | 1 | 1 | 2 | 3 | 4 | 5 | 6 |
2 | 2 | 4 | 6 | 8 | 0 | 2 | |
3 | 3 | 6 | 9 | 2 | 5 | 8 | |
4 | 4 | 8 | 2 | 6 | 0 | 4 | |
5 | 5 | 0 | 5 | 0 | 5 | 0 | |
6 | 6 | 2 | 8 | 4 | 0 | 6 |
Of the 36 possible outcomes in the table above, 6 outcomes have a
ones digit that is equal to 0.
Thus, the probability that the ones digit of the product is 0 is
Solution 2
Since the ones digit of the product is 0, then the product is
divisible by 5 and is even.
Since the possible numbers in the product are 1, 2, 3, 4, 5, 6, then one
of the numbers rolled must be 5.
Since the product is even (and 5 is not), then the other number rolled
must be one of the three even numbers, namely 2, 4, 6.
Thus, the possible pairs of numbers that can be rolled to give a product
whose ones digit is 0, are
Since there are 6 possible rolls for each of the two dice, then there
are
Since 6 of these ordered pairs represent a product whose ones digit is
0, then the required probability is
Answer: (D)
Since
The sum of
Since
By substituting each of these values for
Substituting
Since
This gives
Thus when
Substituting
Since
This gives
Thus when
Substituting
Since
This gives
Substituting
Since
This gives
Thus when
Substituting
Since the numerators are equal, then the denominators must be equal, and
so
Finally, substituting
Since
Thus, there are two pairs of positive integers
Answer: (E)
Since
Since the product of the areas of
The positive divisors of 98 are 1, 2, 7, 14, 49, and 98.
There are exactly two divisors of 98 that are perfect squares, namely 1
and 49.
Since the area of
Square
The perimeter of
If
Since 30 is not given as a possible answer, then
Answer: (B)
If a Gareth sequence begins 10, 8, then the 3rd number in the
sequence is
Thus, the resulting sequence is
The first 5 numbers in the sequence are
Since each new number added to the end of this sequence is determined by
the two previous numbers in the sequence, then this block of 3 numbers
will indeed continue to repeat. (That is, since the block repeats once,
then it will continue repeating.)
The first 30 numbers of the sequence begins with the first 5 numbers,
followed by 8 blocks of
The sum of the first 5 numbers is
The sum of each repeating block is
Thus, the sum of the first 30 numbers in the sequence is
Answer: (E)
Suppose that the length, or the width, or the height of the
rectangular prism is equal to 5.
The product of 5 with any of the remaining digits has a units (ones)
digit that is equal to 5 or it is equal to 0.
This means that if the length, or the width, or the height of the
rectangular prism is equal to 5, then at least one of the two-digit
integers (the area of a face) has a units digit that is equal to 5 or
0.
However, 0 is not a digit that can be used, and each digit from 1 to 9
is used exactly once (that is, 5 cannot be used twice), and so it is not
possible for one of the dimensions of the rectangular prism to equal
5.
Thus, the digit 5 occurs in one of the two-digit integers (the area of a
face).
The digit 5 cannot be the units digit of the area of a face, since this
would require that one of the dimensions be 5.
Therefore, one of the areas of a face has a tens digit that is equal to
5.
The two-digit integers with tens digit 5 that are equal to the product
of two different one-digit integers (not equal to 5) are
Suppose that two of the dimensions of the prism are 7 and 8, and so one
of the areas is 56.
In this case, the digits
Which of these digits is equal to the remaining dimension of the
prism?
It cannot be 1 since the product of 1 and 7 does not give a two-digit
area, nor does the product of 1 and 8.
It cannot be 2 since the product of 2 and 8 is 16 and the digit 6 has
already been used.
It cannot be 3 since
It cannot be 4 since
Finally, it cannot be 9 since
Therefore, it is not possible for 7 and 8 to be the dimensions of the
prism, and thus 6 and 9 must be two of the three dimensions.
Using a similar systematic check of the remaining digits, we determine
that 3 is the third dimension of the prism.
That is, when the dimensions of the prism are
Since the areas of the faces are 18, 27 and 54, the surface area of the
rectangular prism is
Answer: (D)
Solution 1
Begin by colouring the section at the top blue.
Since two circles have the same colouring if one can be rotated to match
the other, it does not matter which section is coloured blue, so we
arbitrarily choose the top section.
There are now 5 sections which can be coloured green.
After choosing the section to be coloured green, there are 4 sections
remaining which can be coloured yellow.
Each of the remaining 3 sections must then be coloured red.
Thus, the total number of different colourings of the circle is
Solution 2
We begin by considering the locations of the three sections coloured
red, relative to one another.
The three red sections could be adjacent to one another, or exactly two
red sections could be adjacent to one another, or no red section could
be adjacent to another red section.
We consider each of these 3 cases separately.
Case 1: All three red sections are adjacent to one another.
Begin by colouring any three adjacent sections red.
Since two circles have the same colouring if one can be rotated to
match the other, it does not matter which three adjacent sections are
coloured red.
Consider the first section that follows the three red sections as we
move clockwise around the circle.
There are 3 choices for the colour of this section: blue, green or
yellow.
Continuing to move clockwise to the next section, there are now 2
choices for the colour of this section.
Finally, there is 1 choice for the colour of the final section, and thus
there are
These 6 colourings are shown below.
Case 2: Exactly two red sections are adjacent to one another.
There are two different possible arrangements in which exactly two
red sections are adjacent to one another.
In the first of these, the next two sections that follow the two
adjacent red sections as we move clockwise around the circle, are both
not red. We call this Case 2a.
In the second of these, the section that follows the two adjacent red
sections as we move clockwise around the circle is not red, but the next
section is. We call this Case 2b.
The arrangements for Cases 2a and 2b are shown below.
Notice that the first of these two circles cannot be rotated to match
the second.
The number of colourings in Case 2a and in Case 2b are each equal to the
number of colourings as in Case 1.
That is, there are 3 choices for the first uncoloured section that
follows the two red sections as we move clockwise around the
circle.
Continuing to move clockwise to the next uncoloured section, there are
now 2 choices for the colour of this section.
Finally, there is 1 choice for the colour of the final section, and thus
there are
These 12 colourings are shown below.
Case 3: No red section is adjacent to another red section.
Begin by colouring any three non-adjacent sections red.
Since two circles have the same colouring if one can be rotated to
match the other, it does not matter which three non-adjacent sections
are coloured red.
In this case, there are 2 possible colourings as shown below.
A circle with any other arrangement of the green, yellow and blue sections can be rotated to match one of the two circles above.
The total number of different colourings of the circle is
Answer: (E)
We can represent the given information in a Venn diagram by first
introducing some variables.
Let
Let
Let
Since 10 students participated in all three activities and no students
participated in fewer than two activities, we complete the Venn diagram
as shown.
Suppose that the total number of students participating in the school
trip was
Since 50% of all students participated in at least hiking and canoeing,
then
Since this number of students,
Similarly,
Since this number of students,
This means that
From the Venn diagram, we see that
Since the total number of participants is
We may now use these equations,
We can then use the values of
Since
However, substituting
Next, we try
When
When
Finally, when
When
In the table below, we continue in this way by using successively
greater multiples of 10 for the value of
20 | 0 | 2 | 8 | |
30 | 5 | 8 | 7 | |
40 | 10 | 14 | 6 | |
50 | 15 | 20 | 5 | |
60 | 20 | 26 | 4 | |
70 | 25 | 32 | 3 | |
80 | 30 | 38 | 2 | |
90 | 35 | 44 | 1 | |
100 | 40 | 50 | 0 |
For values of
Therefore, the sum of all such positive integers
Answer: (B)
The fraction
Answer: (B)
Reading from the graph, the forecast wind speed is less than 20
km/h on Monday, Tuesday, Wednesday, and Sunday.
Thus, Jack will be able to sail alone on 4 days during this 7-day
period.
Answer: (A)
We note that
Since there is no integer
Answer: (B)
Ordering the given list of integers from least to greatest, we
get
The third integer in the ordered list is 0.
Answer: (D)
Solution 1
If
When
Solution 2
Multiplying both sides of the given equation by 5, we get
Answer: (C)
There are 6 possible outcomes when Tallulah rolls a single
standard die once.
She loses if she rolls 2 of these 6 outcomes, and so the probability
that she loses is
Answer: (A)
Solution 1
We may convert the given addition problem to a subtraction
problem.
That is, since
The difference between 2023 and 1013 is
Solution 2
The ones (units) digit of the sum 2023 is 3.
Thus, the ones digit of the sum
Since
The tens digit of the sum 2023 is 2.
Since there is no “carry" from the ones column to the tens column, the
ones digit of the sum
Since
We may confirm that when
The value of
Answer: (B)
Suppose the salad dressing initially contains 300 mL of
oil.
Since the ratio of oil to vinegar is
If the volume of vinegar is doubled, the new volume of vinegar is
Note: We chose to begin with 300 mL of oil, but performing the above
calculations with any starting volume of oil will give the same
Answer: (A)
Before including tax, the combined cost of the three items is
The 5% tax on $15.00 is
Note that we could have calculated the 5% tax on each individual item,
however doing so is less efficient than calculating tax on the $15.00
total.
Answer: (D)
When
In general, when a point is reflected in the
Thus, the vertices of the reflected rectangle are
Of the given possibilities,
Answer: (C)
In the leftmost rectangle, the length of the path along the
rectangle’s diagonal,
Using the Pythagorean Theorem, we get
The path from
Answer: (A)
Since
Since
The sum of the angles inside
Answer: (B)
The number of peaches in the original pile is two more than a
multiple of three.
Of the choices given, 29 is the only number which is two more than a
multiple of three (
Answer: (D)
The sum of each block of 5 repeating integers is
In the first 23 integers, there are 4 such blocks of 5 integers, plus 3
additional integers (since
The sum of the 4 blocks of 5 repeating integers is
Thus, the sum of the first 23 integers is
Answer: (D)
The circumference of each of Bindu’s bike tires is
If the bike tires rotate exactly five times, then the distance travelled
by Bindu’s bike is
Answer: (D)
Solution 1
The sum of all 8 numbers in the list is
When the 8 numbers are arranged in pairs, there are 4 pairs.
The sum of the numbers in each pair is the same, and so this sum is
Therefore, the number paired with 13 is
Note: We may confirm that
Solution 2
Since the sum of the numbers in each pair is the same, then the
largest number in the list must be paired with the smallest number, the
second largest with the second smallest, and so on.
(Can you reason why this must be true?)
That is, the largest and smallest numbers in the list, 45 and 9, must be
paired.
The second largest and second smallest numbers, 41 and 13, must be
paired, and so the number paired with 13 is 41.
Note: We may confirm that
Answer: (E)
The mean (average) is determined by adding the 30 recorded
temperatures, and dividing the sum by 30.
The sum of the temperatures for the first 25 days was
The sum of the temperatures for the last 5 days was
Thus, the mean of the recorded temperatures was
Answer: (C)
We begin by listing, in order, the smallest 2-digit positive
divisors of 630.
We note that by first writing 630 as a product of its prime factors
(
The smallest five 2-digit positive divisors of 630 are
The next largest 2-digit positive divisor of 630 is 30, and we notice
that
That is, 21 and 30 are a pair of 2-digit positive integers whose product
is 630, and they are consecutive in the ordered list of positive
divisors.
Thus, each of
We may check that the divisors that pair with each of
That is,
Thus, the pairs of 2-digit positive integers whose product is 630 are 21 and 30, 18 and 35, 15 and 42, 14 and 45, and 10 and 63, and so there are 5 such pairs.
Answer: (D)
Between 9 a.m. and 10 a.m., Ryan cut
Ryan cut
At 10 a.m., Ryan had cut
Since Ryan cuts
Answer: (C)
Begin by placing four tiles in the squares of the first
row.
The only restriction is that the row must contain one tile of each
colour.
Thus in the first row, there are 4 choices of tile colour for the first
column, 3 choices for the second, 2 for the third, and 1 choice for the
fourth.
That is, there are
For example, using
Suppose that the first row does contain tiles coloured
We will show that there is only one way to arrange the remaining 12
tiles in the grid.
Consider the first square in the second row, that is, the square
directly below the tile coloured
The tile placed in this square cannot be coloured
Also, the tile placed in this square cannot be coloured
Next, consider the colour of the tiles that could be placed in the
second square of row 2.
The tile in this square cannot be coloured
Also, the tile in this square cannot be coloured
Since the first square in this row contains a tile coloured
This means that the tile in the first square of row 2 cannot be coloured
The tile in the second square of row 2 cannot be coloured
Continuing to move right along row 2, the next tile cannot be coloured
That is, the positions of the 4 tiles in row 2 are completely determined
by the tiles in row 1.
Thus for each of the 24 different ways to place the tiles in row 1,
there is exactly one way to place the tiles in row 2.
Repeating the argument, the same is then true for the tiles in row 3 and
row 4; that is, there is exactly one choice for the location of each of
the coloured tiles within each of these two rows as well.
The
You should justify for yourself that each of rows 3 and 4 must contain
tiles exactly as shown.
For each of the 24 different ways to cover the squares in the first
row using one tile of each of the four colours, there is exactly one way
to cover all remaining squares in the grid.
Thus, there are 24 different ways that the tiles can be arranged.
Answer: (B)
Since
Since
Since
The area of
Answer: (D)
Nasrin’s mean (average) speed is determined by dividing the total
distance travelled, which is 9 km, by the total time.
It took Nasrin 2 hours and thirty minutes, or 150 minutes, to canoe into
her camp.
On the return trip, it took her
Thus, the total time for Nasrin to paddle to camp and back was 200
minutes.
Converting to hours, 200 minutes is 3 hours and 20 minutes, and since 20
minutes is
Thus, Nasrin’s mean speed as she paddled to camp and back was
Answer: (E)
To begin, the volume of water in Cylinder B is
After some water is poured from Cylinder B into Cylinder A, the total
volume of water in the two cylinders will be
Let
At this time, the volume of water in Cylinder B is
At this time, the volume of water in Cylinder A is
Thus, the total volume of water in the two cylinders is
When the height of the water in both cylinders is the same, that height is 32 cm.
Answer: (C)
Solution 1
We begin by multiplying the given equation through by 20 to get
Since
We start by trying
This pair for
We may find other solutions to the equation
Adding two 5s is equivalent to increasing the value of
Subtracting five 2s is equivalent to decreasing the value of
Consider
This is a solution since
However, in this case
Thus, we need to go in the other direction.
Consider
This is a solution since
Here,
Next, consider
This is a solution since
Here,
Notice that the sum
This means that doing this 17 more times gets us to
This is a solution since
Notice that it is still the case that
Repeating this process one more time, we get
Since we know that
In total, there are
Solution 2
We begin by rearranging the given equation to isolate
Doing so, we get
Since 2 does not divide 5, then 2 must divide
Since
Since there are 19 even integers from
It is a good idea (and good practice) to at least check that the largest
and smallest of these values of
When
This pair satisfies the given conditions that
Substituting
When
This satisfies the given conditions that
Substituting
At this point we can be confident that for each of the 19 even
integer values of
Answer: (B)
For any triangle, the sum of the lengths of two sides is always
greater than the length of the third side. This property is known as the
triangle inequality.
If for example the side lengths of a triangle are
Consider choosing the integers
Since
Consider choosing the integers
Since
Consider choosing the integers
Since
However, the remaining possible choice of three side lengths,
Thus, without using the value of
This means that we need to determine values of
There are six possible ways to choose two integers from the list
Thus for each value of
For each value of
Next, we use the triangle inequality to determine the restrictions on
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
Since
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
In a triangle with side lengths
To satisfy all three inequalities,
Thus, the possible values of
Recall that for each value of
Clearly for values of
In the table below, we summarize our work by placing a checkmark if the
triangle satisfies the triangle inequality and then counting the number
of such triangles.
Number of triangles | ||||||||
---|---|---|---|---|---|---|---|---|
7 | ✓ | ✓ | ✓ | 3 | ||||
8 | ✓ | ✓ | ✓ | ✓ | 4 | |||
9 | ✓ | ✓ | ✓ | ✓ | 4 | |||
11 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | 6 | |
12 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | 6 | |
14 | ✓ | ✓ | ✓ | ✓ | 4 | |||
15 | ✓ | ✓ | ✓ | ✓ | 4 | |||
16 | ✓ | ✓ | ✓ | 3 |
Therefore, there are exactly four different values of
Answer: (A)