1998 PMWC Problems
Contents
[hide]- 1 Problem I1
- 2 Problem I2
- 3 Problem I3
- 4 Problem I4
- 5 Problem I5
- 6 Problem I6
- 7 Problem I7
- 8 Problem I8
- 9 Problem I9
- 10 Problem I10
- 11 Problem I11
- 12 Problem I12
- 13 Problem I13
- 14 Problem I14
- 15 Problem I15
- 16 Problem T1
- 17 Problem T2
- 18 Problem T3
- 19 Problem T4
- 20 Problem T5
- 21 Problem T6
- 22 Problem T7
- 23 Problem T8
- 24 Problem T9
- 25 Problem T10
Problem I1
Calculate:
Problem I2
Problem I3
Problem I4
Suppose in each day on a certain planet, there are only 10 hours and every hour has 100 minutes. What is the measure, in degrees, of the acute angle formed by the hour hand and the minute hand at 6 o'clock 75 minutes?
Problem I5
There were many balls which were distributed into 1998 boxes and all these boxes were arranged in a row. If the second box from the left-hand contained 7 balls and any 4 consecutive boxes always had a total of 30 balls, how many balls were there in the right-hand box?
Problem I6
After a mathematics test, each of the 25 students in the class got a quick look at the teacher’s grade sheet. Each student noticed five A’s. No student saw all the grades and no student saw her or his own grade. What is the minimum number of students who scored an A on this test?
Problem I7
Problem I8
A boy arranges three kinds of books which are 30 mm, 24 mm, and 18 mm thick, respectively. He places only books of the same thickness into 3 stacks of equal height, and wants to make the height as small as possible. How many books would be used in this arrangement?
Problem I9
How many triangles are there with side lengths whole numbers and with a perimeter of 10 cm ?
Problem I10
Find the number of factors of 960.
Problem I11
What is the units digit of ?
Problem I12
Problem I13
Every year there is at least one Friday the thirteenth, but no year has more than three. This year there are exactly three : in February, March and November. When will the next year be that contains exactly three Friday the thirteenths?
Problem I14
Problem I15
Construct a rectangle by putting together nine squares with sides equal to 1, 4, 7, 8, 9, 10, 14, 15 and 18. What is the sum of the areas of the squares on the 4 corners of the resulting rectangle ?
Problem T1
What is the 1998th number in the following sequence ? 1, -2, 2, -3, 3, -3, 4, -4, 4, -4, 5, -5, 5, -5, 5, -6, 6, -6, 6, -6, 6,........ Solution
Problem T2
Tom started work on a job alone for 30 days. Jerry continued the job alone for 5 days, and finally they worked together for another 10 days to complete that job. For the same job, if Tom and Jerry work together, they can complete it in 20 days. Assuming Tom and Jerry each work at a constant rate throughout, how many days will Tom take to complete that job alone? Solution
Problem T3
The set L consists of all positive integers which leave a remainder of 1 when divided by 3. A member of L (other than 1) is called an L-prime if it is not the product of two members of L, other than itself and 1. Which is the 8th L-prime? Solution
Problem T4
There are many circles on a plane. Each is divided into four parts by two mutually perpendicular diameters. Each part is painted either red, yellow or blue. No matter how the circles are rotated in the plane, they are different from one another. At most how many circles are painted with all three colors? Solution
Problem T5
Find the largest positive integer with the following properties : (a) all the digits are different. (b) each two consecutive digits form a number divisible by either 17 or 23. Solution
Problem T6
There were 3 students in an athletics competition of at least two events. Each student participated in all events. In each event, student who finished second got more points than the student who finished third but less than the student who finished first. All scores were positive integers and all the events used the same 3 scores. At the end of the competition, the total scores of the 3 students were 5, 9 and 16. Determine the first-place score for each event. Solution
Problem T7
A leaf is torn from a book of not more than 500 pages. The sum of the remaining pages numbers is 19905. What is the sum of the two page numbers of the leaf torn out ? Solution
Problem T8
A rectangular lawn is surrounded by a path 1 meter in width and forming a larger rectangle. The dimensions of the lawn are in whole number of metres and the area of the path equals the area of the lawn. Find the smallest possible area of the path in metres . Solution
Problem T9
A, B, C, D and E play a game in which each is either a lion or a goat. A lion’s statement is always false and a goat’s statement is always true. A says B is not a goat. C says D is a lion. E says A is not a lion. B says C is not a goat. D says that E and A are different kinds of animals. Who are the lions? Solution
Problem T10
In the following expression, each letter represents a digit. Same digits are represented by the same letter, and different letters stand for different digits. Any digit can replace any square, find the 5-digit number ABCBA?