Which proportion yields a different number for the unknown compared to the others?
- A. 2/3 = x/6
- B. 4/5 = x/10
- C. 3/4 = x/8
- D. 5/6 = x/12
Correct Answer: D
Rationale: To find the value of x in each proportion, cross multiply. For proportion A, x = 4; for B, x = 8; for C, x = 6; and for D, x = 10. Hence, proportion D yields a different value for x compared to the others. Choices A, B, and C all result in unique values for x, but these values are distinct from the value obtained in proportion D.
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Half of a circular garden with a radius of 11.5 feet needs weeding. Find the area in square feet that needs weeding. Round to the nearest hundredth. Use 3.14 for π.
- A. 2.4
- B. 207.64
- C. 15.1
- D. 30.1
Correct Answer: B
Rationale: The formula for the area of a full circle is calculated as Area = π (radius²). When finding the area of half a circle, we multiply by 0.5. Thus, the formula becomes Area = 0.5 π (radius²). Given that the radius of the circular garden is 11.5 feet, the calculation using π = 3.14 is as follows: Area = 0.5 3.14 (11.5²) = 0.5 3.14 132.25 = 0.5 415.27 = 207.64 square feet. Therefore, the correct answer is B. Choices A, C, and D are incorrect because they do not reflect the correct calculation for finding the area of half a circular garden with a radius of 11.5 feet.
If a tree grows an average of 4.2 inches in a day, what is the rate of change in its height per month? Assume a month is 30 days.
- A. 0.14 inches per month
- B. 4.2 inches per month
- C. 34.2 inches per month
- D. 126 inches per month
Correct Answer: D
Rationale: The tree grows at an average rate of 4.2 inches per day. To find the rate of change per month, multiply the daily growth rate by the number of days in a month (30 days):
4.2 inches/day 30 days = 126 inches per month.
Therefore, the rate of change in the tree's height is 126 inches per month, making option D the correct answer. Option A is incorrect because it miscalculates the rate based on daily growth. Option B is incorrect as it doesn't account for the total days in a month. Option C is incorrect as it overestimates the monthly growth rate.
What is the difference between two negative numbers?
- A. Negative number
- B. Positive number
- C. Zero
- D. Not enough information
Correct Answer: B
Rationale: The correct answer is B: 'Positive number.' When you subtract one negative number from another negative number, the result can be a positive number. For example, the difference between -5 and -3 is 2, which is a positive number. Choice A, 'Negative number,' is incorrect because the result of subtracting two negative numbers can be positive. Choice C, 'Zero,' is incorrect because the difference between two negative numbers is not always zero. Choice D, 'Not enough information,' is incorrect because there is enough information to determine that the difference between two negative numbers can be a positive number.
What is 4 + 5 + 12 + 9?
- A. 20
- B. 30
- C. 40
- D. 50
Correct Answer: B
Rationale: The correct answer is B: 30. To find the sum, you need to add 4 + 5 + 12 + 9, which equals 30, not 40 as stated in the original rationale. Choice A (20) is incorrect because it does not account for the correct addition of the numbers provided. Choice C (40) is incorrect as it represents the sum of the numbers incorrectly. Choice D (50) is also incorrect as it is not the sum of the given numbers.
Jayden rides his bike for 5/8 miles. He takes a break and rides another 3/4 miles. How many miles does he ride?
- A. 1 3/8 miles
- B. 1 1/2 miles
- C. 1 7/8 miles
- D. 2 miles
Correct Answer: A
Rationale: To find the total distance Jayden rides, you need to add the fractions 5/8 + 3/4. To add these fractions, you must ensure they have a common denominator. In this case, the common denominator is 8. So, 5/8 + 3/4 = 5/8 + 6/8 = 11/8. Since 11/8 can be simplified to 1 3/8, Jayden rides a total of 1 3/8 miles. Choice B (1 1/2 miles), Choice C (1 7/8 miles), and Choice D (2 miles) are incorrect as they do not accurately represent the total distance calculated by adding the two fractions, which is 1 3/8 miles.