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Solve for y if y = 3: 4y + 21/y
- A. 19
- B. 7.7
- C. 23/3
- D. 11
Correct Answer: A
Rationale: To solve the expression 4y + 21/y when y = 3, substitute y = 3: 4 * 3 + 21 / 3 = 12 + 7 = 19. Therefore, the correct answer is 19. Choice A, '19,' is the correct result of the expression when y = 3. Choice B, '7.7,' is incorrect as the correct answer is an integer, not a decimal. Choice C, '23/3,' is incorrect as it is not the simplified integer result of the expression. Choice D, '11,' is incorrect as it does not result from the given expression when y = 3.
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If two workers can finish building a play set in 18 hours, how long will it take 4 workers to build 3 play sets?
- A. 27 hours
- B. 36 hours
- C. 24 hours
- D. 54 hours
Correct Answer: A
Rationale: If 2 workers can complete building one play set in 18 hours, it means one worker would take 36 hours to complete the same task. When the number of workers is doubled to 4, the time is halved, so 4 workers would take 18 hours to build one play set. To build 3 play sets, the total time needed would be 3 times the time for one play set, which equals 54 hours. Therefore, 4 workers can build 3 play sets in 27 hours, making choice A the correct answer. Choices B, C, and D are incorrect because they do not account for the correct relationship between the number of workers and the time required to complete the task.
If Andy runs five times as long as Jake, and Jake runs 24.5 miles each week, how many miles does Andy run in a day?
- A. 17.5
- B. 17.7
- C. 16.5
- D. 18.2
Correct Answer: A
Rationale: To find how many miles Andy runs in a day, we need to calculate the distance Andy runs in a week. Since Andy runs five times as long as Jake, Andy runs 5 * 24.5 = 122.5 miles per week. To convert this to miles per day, we divide by 7 (days in a week): 122.5 / 7 = 17.5 miles per day. Therefore, the correct answer is A. Choices B, C, and D are incorrect as they do not accurately reflect the calculation based on the given ratio.
What is the greatest common factor (GCF) of 12 and 18?
- A. 2
- B. 3
- C. 6
- D. 9
Correct Answer: C
Rationale: The greatest common factor (GCF) of two numbers is the largest number that divides both numbers without leaving a remainder. To find the GCF of 12 and 18, we factorize each number: 12 = 2 x 2 x 3 and 18 = 2 x 3 x 3. The common factors are 2 and 3. The GCF is the product of these common factors, which is 6. Therefore, 6 is the greatest common factor of 12 and 18. Choice A (2) and Choice B (3) are factors of both numbers but not the greatest common factor. Choice D (9) is not a factor of both 12 and 18, making it incorrect.
A school has 500 students, and 60% of them are girls. How many girls are there in the school?
- A. 250 girls
- B. 300 girls
- C. 200 girls
- D. 350 girls
Correct Answer: B
Rationale: Correct! To find out how many girls are in the school, you need to calculate 60% of 500. 60% of 500 is 0.6 * 500 = 300. Therefore, there are 300 girls in the school. Choice A (250 girls) is incorrect because 60% of 500 is not 250. Choice C (200 girls) is incorrect as it is less than 300. Choice D (350 girls) is incorrect as it is more than 300.
Two buildings in downtown Chicago stand across the river. The first building is 1,700 feet tall and casts a shadow of 525 feet. If the second building is 1,450 feet tall, how long will its shadow be?
- A. 478 feet
- B. 455 feet
- C. 448.5 feet
- D. 450 feet
Correct Answer: C
Rationale: To find the shadow of the second building, we use the ratio of heights to shadows: 1,700/525 = 1,450/x. Solving for x gives x = (525 1,450)/1,700 = 448.5. Therefore, the shadow of the second building will be approximately 448.5 feet long.
Choice A (478 feet) is incorrect because it is not the result of the correct calculation. Choice B (455 feet) is incorrect as it does not match the accurate answer obtained through the calculation. Choice D (450 feet) is incorrect as it does not reflect the correct length of the shadow of the second building.