Tuesday, February 27, 2018
(in North America and South America)
Wednesday, February 28, 2018
(outside of North American and South America)
©2017 University of Waterloo
Evaluating,
Answer: (D)
Since the maximum temperature was
Answer: (B)
The expression
When
Answer: (A)
The fraction
The fraction
Therefore, the integers between these two fractions are
Answer: (B)
If
If
If
If
Thus,
This means that
Answer: (D)
Since
Since
Since
Answer:(E)
Since Bev has driven 312 km and still has 858 km left to drive, the distance from Waterloo to Marathon is
The halfway point of the drive is
To reach this point, she still needs to drive
Answer: (B)
A line segment joining two points is parallel to the
Here, this means that
(We can check that when
Answer: (A)
Since the area of rectangle
Since
Since
In
Therefore, its area is
Answer: (B)
For any real number
Since
Of the given points, only
Answer: (C)
Since
Since the 8 red balls represent
Answer: (C)
There is
There are
Finally, there is
In total, there are thus
Answer:(E)
We would like to find the first time after 4:56 where the digits are consecutive digits in increasing order.
It would make sense to try 5:67, but this is not a valid time.
Similarly, the time cannot start with 6, 7, 8 or 9.
No time starting with 10 or 11 starts with consecutive increasing digits.
Starting with 12, we obtain the time 12:34. This is the first such time.
We need to determine the length of time between 4:56 and 12:34.
From 4:56 to 11:56 is 7 hours, or
From 11:56 to 12:00 is 4 minutes.
From 12:00 to 12:34 is 34 minutes.
Therefore, from 4:56 to 12:34 is
Answer: (A)
The line with equation
When this line is translated, its slope does not change.
When this line is translated 3 units to the right and 2 units down, every point on the line is translated 3 units to the right and 2 units down. Thus, the point
Therefore, the new line has slope 1 and passes through
Thus, its equation is
The
Answer: (C)
Each entry in the grid must be a divisor of the product of the numbers in its row and the product of the numbers in its column.
Only two of the products are multiples of 5, namely 160 and 135.
This means that the 5 must go in the second row and third column.
From this, we can see that the product of the other two numbers in the second row is
Since all of the entries are between 1 and 9, then the remaining two numbers in this row must be 3 and 9.
Since 9 is not a divisor of 21, then 9 must be in the middle column.
This means that the product of the remaining numbers in the middle column is
This means that the remaining digits in the middle column are 3 and 4, or 2 and 6. (These are the only factor pairs of 12 from the list of possible entries.)
Since 3 already occurs in the second row, then the entries in the second column must be 2 and 6.
Since 6 is not a divisor of 56, then 6 cannot go in the first row.
This means that 6 goes in the third row and so
We can complete the grid as follows:
Answer:(D)
Solution 1
If point
Since points
One way to see this is to recognize that there are two possible lines through
Solution 2
Consider the line segment
Suppose that the point
Since
Since
In other words, point
Since these two circles intersect in exactly two points, then there are two possible locations for
Answer: (C)
The side length of the square is 2 and
Thus,
Using the Pythagorean Theorem in
Similarly,
Using the Pythagorean Theorem in
Using the cosine law in
Answer: (A)
Suppose that
Squaring both sides, we obtain
Since
Let’s make the assumption that
Squaring both sides of the second equation, we obtain
So we have
By inspection, we might see that
If we didn’t see this by inspection, we could note that
Factoring, we get
Since
Thus,
When
Therefore,
We note that
Answer:(E)
Solution 1
Over the first 3 minutes of the race, Peter ran 48 m farther than Radford. Here is why:
We note that at a time of 0 minutes, Radford was at the 30 m mark.
If Radford ran
Since Peter is 18 m ahead of Radford after 3 minutes, then Peter is at the
This means that, in 3 minutes, Peter ran
Since each runs at a constant speed, then Peter runs
Since Peter finishes the race after 7 minutes, then Peter runs for another 4 minutes.
Over these 4 minutes, he runs
After 3 minutes, Peter was 18 m ahead of Radford.
Therefore, after 7 minutes, Peter is
Solution 2
As in Solution 1, suppose that Radford ran
Since Peter’s speed is constant, he runs
Since Radford’s speed is constant, he runs
This means that Peter runs a total of
Also, Radford is
Thus, Radford’s distance from the finish line, in metres, is
Answer: (D)
We count the positive integers
The product
This occurs exactly when
These are the even integers from 2 to 2018, inclusive, and there are
The product
We note further that for every integer
When
When
This pattern continues giving a negative value for
There are
When
Therefore, there are
We should further justify the pattern that we found above.
Suppose that
Then
In other words, when
In other words, when
Since the total number of factors is 1009, which is odd, then the number of negative factors is odd and so the product is negative.
In a similar way, we can show that if
This confirms that this pattern continues.
Answer: (C)
Substituting
Since
Rearranging the given equation, we obtain
Thus,
(For example,
Now
We note that
Finally,
Thus, the sum of the first 2018 terms is
Answer:(E)
First, we find the coordinates of the points
Equating values of
We rewrite the left side as
Since
Since
Since
Our next step is to determine the area of
Since the area of
To find the area of
The area of
Trapezoid
Since the coordinates of
Since the coordinates of
Also,
Thus, the area of trapezoid
Combining these, the area of
Since this area equals 80, then
This means that the slope of the line is
Answer: (D)
We are told that
In particular, this equation holds when
Substituting
Since
Therefore, the possible values of
These yield values for
We need to confirm that each of these values for
If
When
Expanding the right side gives
The quadratic
Similarly, if
Also, if
Similarly, if
Therefore, the possible values of
The sum of these values is
Answer: (B)
We use the notation “
Yellow buckets
1/0/0: With 1 puck to distribute, the distribution will always be 1/0/0.
Blue buckets
Since there are 2 pucks to distribute amongst the three buckets, then there is a total of
2/0/0: There are 3 ways in which the 2 pucks end up in the same bucket (1 way for each of the 3 buckets). The probability of this is
1/1/0: Thus, there are
Red buckets
With 3 pucks to distribute amongst 3 buckets, there is a total of
3/0/0: There are 3 ways in which the 3 pucks end up in the same bucket (1 way for each of the 3 buckets). The probability of this is
1/1/1: There are
2/1/0: Thus, there are
Green buckets
With 4 pucks to distribute amongst 3 buckets, there is a total of
4/0/0: There are 3 ways in which the 4 pucks end up in the same bucket (1 way for each of the 3 buckets). The probability of this is
3/1/0: There are
2/1/1: There are
2/2/0: Thus, there are
For a green bucket to contain more pucks than each of the other 11 buckets, the following possible distributions exist with probabilities as shown:
Green | Red | Blue | Yellow | Probability |
---|---|---|---|---|
4/0/0 ( |
Any ( |
Any ( |
Any ( |
|
3/1/0 ( |
Any but 3/0/0 ( |
Any ( |
Any ( |
|
2/1/1 ( |
1/1/1 ( |
1/1/0 ( |
Any ( |
A 2/2/0 distribution of pucks among green buckets cannot satisfy the desired conditions because there would be not be a single green bucket with more pucks in it than any other bucket, as there would be two green buckets containing the same number of pucks.
Therefore, the overall probability is
Answer: (B)
Suppose that
Case 1:
Suppose that
Since
Since
This means that if
So if
If
Since
If
Since
If
Since
If
Since
Therefore, in the case where
Since there are
Case 2:
Here, the equation
For each possible value of
Since
Case 3:
Here, the equation
As
As
The pairs of integers in the first and second lists that differ by at most 9 are
101 and 99 (which give
404 and 396 (which give
707 and 704 (which give
Since
In total, there are thus
The sum of the digits of
Answer: (C)