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What is the result of (4.71 10^3) - (2.98 10^2)? Which of the following is the correct simplified expression?
- A. 1.73 10
- B. 4.412 10^2
- C. 1.73 10^3
- D. 4.412 10^3
Correct Answer: D
Rationale: The correct answer is D: 4.412 10^3. To simplify the expression, rewrite 4.71 10^3 as 47.1 10^2. Subtract the values in front of 10^2: 47.1 - 2.98 = 44.12. Rewriting this gives 44.12 10^2 = 4.412 10^3. Choice A is incorrect as it does not account for the correct subtraction result. Choice B is incorrect as it does not correctly simplify the expression. Choice C is incorrect as it provides an incorrect power of 10 in the simplified expression.
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A circular swimming pool has a circumference of 49 feet. What is the diameter of the pool?
- A. 15.6 feet
- B. 17.8 feet
- C. 49 feet
- D. 153.9 feet
Correct Answer: A
Rationale: The formula for the circumference of a circle is C = πd, where C is the circumference and d is the diameter. Given C = 49 feet, we can rearrange the formula to solve for d: 49 feet = πd. To find the diameter, we divide both sides by π, giving us d = 49 feet / π ≈ 15.6 feet. Therefore, the diameter of the swimming pool is approximately 15.6 feet. Choices B, C, and D are incorrect because they do not align with the calculation based on the formula for the circumference of a circle.
Which of the following is the y-intercept of the line whose equation is 7y − 42x + 7 = 0?
- A. (1/6, 0)
- B. (6, 0)
- C. (0, −1)
- D. (−1, 0)
Correct Answer: C
Rationale: To find the y-intercept, set x = 0 in the equation 7y − 42x + 7 = 0. This simplifies to 7y - 42(0) + 7 = 0, which gives 7y = -7. Solving for y, we get y = -1. Therefore, the y-intercept is where x = 0, so the correct answer is (0, -1).
Choice A (1/6, 0) is incorrect as it does not satisfy the given equation when x = 0. Choice B (6, 0) is incorrect as it represents the x-intercept. Choice D (-1, 0) is incorrect as it does not correspond to the y-intercept of the given equation.
Melissa is ordering fencing to enclose a square area of 5625 square feet. How many feet of fencing does she need?
- A. 75 feet
- B. 150 feet
- C. 300 feet
- D. 5,625 feet
Correct Answer: C
Rationale: To find the side length of the square, we take the square root of the area: √5625 ft² = 75 ft. The perimeter of a square is 4 times its side length, so the fencing needed is 4 75 ft = 300 ft. Therefore, Melissa needs 300 feet of fencing to enclose the square area of 5625 square feet. Option A (75 feet) is the side length of the square, not the fencing needed. Option B (150 feet) is half of the correct answer and does not account for all sides of the square. Option D (5,625 feet) is the total area, not the length of fencing required.
A woman's dinner bill comes to $48.30. If she adds a 20% tip, which of the following will be her total bill?
- A. $9.66
- B. $38.64
- C. $48.30
- D. $57.96
Correct Answer: D
Rationale: To calculate the total bill after adding a 20% tip, you need to find 120% of the original bill. This is because adding a 20% tip means paying 120% of the bill. So, $48.30 120/100 = $57.96. Therefore, the correct answer is $57.96. Choice A ($9.66) is incorrect as it represents only the 20% tip amount. Choice B ($38.64) is incorrect as it is the original bill amount without the tip. Choice C ($48.30) is incorrect as it is the original bill amount and does not include the additional 20% tip.
A sandwich shop earns $4 for every sandwich (s) it sells, $2 for every drink (d), and $1 for every cookie (c). If this is all the shop sells, which of the following equations represents what the shop's revenue (r) is over three days?
- A. r = 4s + 2d + 1c
- B. r = 8s + 4d + 2c
- C. r = 12s + 6d + 3c
- D. r = 16s + 8d + 4c
Correct Answer: A
Rationale: Let s be the number of sandwiches sold. Each sandwich earns $4, so selling s sandwiches at $4 each results in revenue of $4s. Similarly, d drinks at $2 each give $2d of income, and cookies bring in $1c. Summing these values gives total revenue = 4s + 2d + 1c. Therefore, option A, r = 4s + 2d + 1c, correctly represents the shop's revenue. Choices B, C, and D are incorrect because they incorrectly multiply the prices of each item by more than one day's sales, which would overstate the total revenue for a three-day period.