Arab Mathematical Olympiad (ArMO)

Description: The Arab Mathematical Olympiad (ArMO) is a prestigious mathematics competition for high school students from Arab countries. The competition is held annually, and the top-performing students are awarded medals and prizes.
Number of Questions: 15
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Tags: mathematics olympiad algebra geometry number theory
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What is the sum of the first 100 positive integers?

  1. 5050

  2. 5150

  3. 5250

  4. 5350


Correct Option: A
Explanation:

The sum of the first n positive integers is given by the formula n(n+1)/2. Therefore, the sum of the first 100 positive integers is 100(101)/2 = 5050.

What is the area of a circle with radius 5 cm?

  1. 25π cm^2

  2. 50π cm^2

  3. 75π cm^2

  4. 100π cm^2


Correct Option: A
Explanation:

The area of a circle is given by the formula πr^2. Therefore, the area of a circle with radius 5 cm is π(5)^2 = 25π cm^2.

What is the volume of a cube with side length 4 cm?

  1. 64 cm^3

  2. 128 cm^3

  3. 192 cm^3

  4. 256 cm^3


Correct Option: A
Explanation:

The volume of a cube is given by the formula s^3. Therefore, the volume of a cube with side length 4 cm is 4^3 = 64 cm^3.

What is the equation of a line that passes through the points (2, 3) and (5, 7)?

  1. y = 2x + 1

  2. y = 2x - 1

  3. y = x + 3

  4. y = x - 3


Correct Option: A
Explanation:

The equation of a line that passes through two points (x1, y1) and (x2, y2) is given by the formula y - y1 = (y2 - y1)/(x2 - x1) * (x - x1). Substituting the values of the two points, we get y - 3 = (7 - 3)/(5 - 2) * (x - 2). Simplifying this equation, we get y = 2x + 1.

What is the solution to the equation x^2 - 4x + 3 = 0?

  1. x = 1, x = 3

  2. x = -1, x = -3

  3. x = 2, x = 3

  4. x = -2, x = -3


Correct Option: A
Explanation:

We can solve this equation using the quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a. Substituting the values of a, b, and c, we get x = (-(-4) ± √((-4)^2 - 4(1)(3))) / 2(1). Simplifying this equation, we get x = (4 ± √(16 - 12)) / 2. Further simplifying, we get x = (4 ± √4) / 2. Therefore, the solutions to the equation are x = 1 and x = 3.

What is the greatest common divisor (GCD) of 12 and 18?

  1. 2

  2. 3

  3. 6

  4. 9


Correct Option: C
Explanation:

The GCD of two numbers is the largest positive integer that divides both numbers without leaving a remainder. We can find the GCD of 12 and 18 by using the Euclidean algorithm: 18 = 12 * 1 + 6, 12 = 6 * 2 + 0. Therefore, the GCD of 12 and 18 is 6.

What is the least common multiple (LCM) of 12 and 18?

  1. 36

  2. 54

  3. 72

  4. 90


Correct Option: A
Explanation:

The LCM of two numbers is the smallest positive integer that is divisible by both numbers. We can find the LCM of 12 and 18 by using the formula LCM = (a * b) / GCD. Substituting the values of a, b, and GCD, we get LCM = (12 * 18) / 6 = 36.

What is the value of the expression 2^3 + 3^2 - 4^1?

  1. 11

  2. 13

  3. 15

  4. 17


Correct Option: C
Explanation:

We can evaluate the expression by following the order of operations: 2^3 = 8, 3^2 = 9, 4^1 = 4. Therefore, the value of the expression is 8 + 9 - 4 = 15.

What is the value of the expression (2 + 3i)(4 - 5i)?

  1. -11 + 22i

  2. -11 - 22i

  3. 11 + 22i

  4. 11 - 22i


Correct Option: D
Explanation:

We can evaluate the expression by using the distributive property: (2 + 3i)(4 - 5i) = 2(4 - 5i) + 3i(4 - 5i). Simplifying this expression, we get 8 - 10i + 12i - 15i^2. Since i^2 = -1, we can simplify further to get 11 - 22i.

What is the probability of getting a head when flipping a coin?

  1. 1/2

  2. 1/3

  3. 1/4

  4. 1/6


Correct Option: A
Explanation:

When flipping a coin, there are two possible outcomes: head or tail. Since both outcomes are equally likely, the probability of getting a head is 1/2.

What is the probability of getting a sum of 7 when rolling two dice?

  1. 1/6

  2. 1/12

  3. 1/18

  4. 1/24


Correct Option: A
Explanation:

When rolling two dice, there are 36 possible outcomes. The outcomes that result in a sum of 7 are (1, 6), (2, 5), (3, 4), (4, 3), (5, 2), and (6, 1). Therefore, the probability of getting a sum of 7 is 6/36 = 1/6.

What is the next term in the sequence 1, 4, 9, 16, ...?

  1. 21

  2. 25

  3. 28

  4. 31


Correct Option: B
Explanation:

The sequence is a sequence of squares of natural numbers. The next term in the sequence is the square of the next natural number, which is 5. Therefore, the next term in the sequence is 5^2 = 25.

What is the sum of the first 100 prime numbers?

  1. 24133

  2. 24233

  3. 24333

  4. 24433


Correct Option: A
Explanation:

The sum of the first 100 prime numbers is 24133.

What is the largest prime number less than 100?

  1. 97

  2. 95

  3. 93

  4. 91


Correct Option: A
Explanation:

The largest prime number less than 100 is 97.

What is the smallest positive integer that is divisible by 2, 3, and 5?

  1. 30

  2. 45

  3. 60

  4. 75


Correct Option: A
Explanation:

The smallest positive integer that is divisible by 2, 3, and 5 is 30.

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