Nokea
In his stamp collection, Bruno has 15 more stamps from Europe than from Africa, and 18 more stamps from Asia than from Africa. If he has 27 stamps from Europe, how many Asian stamps does he have?
- A. 12
- B. 22
- C. 30
- D. 40
Correct Answer: C
Rationale: Since Bruno has 27 stamps from Europe, which is 15 more than from Africa, he must have 27 - 15 = 12 stamps from Africa. Since he also has 18 more stamps from Asia than from Africa, he must have 12 + 18 = 30 stamps from Asia. Therefore, Bruno has 30 Asian stamps. Choice A (12) is the number of stamps Bruno has from Africa, not Asia. Choices B (22) and D (40) are not derived from the correct calculations based on the given information.
You may also like to solve these questions
What is 110% of 40?
- A. 60
- B. 50
- C. 55
- D. 44
Correct Answer: D
Rationale: To find 110% of a number, you multiply the number by 1.10. Therefore, 1.10 * 40 = 44. Since 110% of 40 is 44, the correct answer is D. Choice A (60) is the result of finding 150% of 40, not 110%. Choice B (50) is incorrect as it represents 125% of 40. Choice C (55) is not the correct answer as it corresponds to 137.5% of 40.
A lab needs 200ml of a 5% salt solution. They only have a 10% solution. How much 10% solution and water should be mixed?
- A. 100ml 10% solution, 100ml water
- B. 150ml 10% solution, 50ml water
- C. 160ml 10% solution, 40ml water
- D. 200ml 10% solution, 0ml water
Correct Answer: B
Rationale: Rationale:
1. Let x be the volume of the 10% solution needed and y be the volume of water needed.
2. The total volume of the final solution is 200ml, so x + y = 200.
3. The concentration of the final solution is 5%, so the amount of salt in the final solution is 0.05 * 200 = 10g.
4. The amount of salt in the 10% solution is 0.1x, and the amount of salt in the water is 0, so the total amount of salt in the final solution is 0.1x.
5. Since the total amount of salt in the final solution is 10g, we have 0.1x = 10.
6. Solving for x, we get x = 100ml.
7. Substituting x =
Relatively prime numbers share no common factors other than 1. Which of the following pairs of numbers are relatively prime?
- A. 12 and 16
- B. 15 and 17
- C. 20 and 24
- D. 28 and 36
Correct Answer: B
Rationale: Rationale:
- Relatively prime numbers are numbers that share no common factors other than 1.
- To determine if two numbers are relatively prime, we need to find the greatest common divisor (GCD) of the two numbers. If the GCD is 1, then the numbers are relatively prime.
- Let's calculate the GCD for each pair of numbers:
A) GCD(12, 16) = 4, not relatively prime
B) GCD(15, 17) = 1, relatively prime
C) GCD(20, 24) = 4, not relatively prime
D) GCD(28, 36) = 4, not relatively prime
Therefore, the pair of numbers 15 and 17 are relatively prime because their greatest common divisor is 1, meaning they share no common factors other than 1.
A cake recipe calls for 2½ cups of flour. How many cups are needed to make 6 cakes?
- A. 12.5 cups
- B. 13 cups
- C. 14 cups
- D. 15 cups
Correct Answer: D
Rationale: To make one cake, you need 2½ cups of flour. To make 6 cakes, you would need 6 times the amount of flour for one cake, which is 2½ x 6 = 15 cups. Therefore, the correct answer is 15 cups. Choices A, B, and C are incorrect as they do not correctly calculate the total amount of flour needed for 6 cakes.
Which numeric system was a base 20 system?
- A. Mayan
- B. Babylonian
- C. Roman
- D. Arabic
Correct Answer: A
Rationale: The Mayan numeric system was a base 20 system, known as vigesimal, as it used base 20 numerals. This system was unique and employed a combination of symbols and positional notation to represent numbers. The Babylonian system was a base 60 system, Roman numerals were based on combinations of letters, and Arabic numerals are in base 10, making choices B, C, and D incorrect.