Nokea
4.67 miles is equivalent to how many kilometers to three significant digits?
- A. 7.514 km
- B. 7.51 km
- C. 2.90 km
- D. 2.902 km
Correct Answer: B
Rationale: To convert miles to kilometers, we use the conversion factor of 1 mile ≈ 1.60934 km. Therefore, 4.67 miles * 1.60934 km/mile = 7.514 km. When rounded to three significant digits, the answer is 7.51 km. Choice A of 7.514 km is the correct conversion, but the question asked for the answer to be rounded to three significant digits, making choice B, 7.51 km, the most precise and correct option. Choices C and D are incorrect conversions and do not match the correct conversion of 4.67 miles to kilometers.
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Express 3 5/7 as an improper fraction.
- A. 26/7
- B. 21/7
- C. 22/7
- D. 26/5
Correct Answer: A
Rationale: To convert a mixed number to an improper fraction, multiply the whole number by the denominator of the fraction, then add the numerator. In this case, 3 * 7 + 5 = 21 + 5 = 26. So, 3 5/7 as an improper fraction is 26/7. Choice B (21/7) is incorrect because it represents the original fraction 3 5/7. Choice C (22/7) is incorrect and represents a different fraction. Choice D (26/5) is incorrect and does not reflect the proper conversion of the mixed number to an improper fraction.
If Mom's car drove 72 miles in 90 minutes, how fast did she drive in feet per second?
- A. 0.8 feet per second
- B. 48.9 feet per second
- C. 0.009 feet per second
- D. 70.4 feet per second
Correct Answer: D
Rationale: To convert miles per hour to feet per second, first convert time to hours: 90 minutes = 1.5 hours. Then, calculate the speed in miles per hour: 72 miles in 1.5 hours = 48 mph. Finally, convert mph to feet per second using the conversion factor 1 mph = 1.47 feet per second: 48 mph * 1.47 = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choices A, B, and C are incorrect because they do not reflect the correct conversion from miles per hour to feet per second.
What is the simplified form of the expression (x^2 + 2x)/(x)?
- A. x + 2
- B. x^2 + 2
- C. x(x + 2)
- D. 1 + 2/x
Correct Answer: A
Rationale: To simplify the expression (x^2 + 2x)/(x), we factor out x from the numerator to get x(x + 2) and then cancel the x in the denominator. This simplifies to x + 2, making choice A the correct answer. Choice B (x^2 + 2) is incorrect as it does not account for the division by x. Choice C (x(x + 2)) is also incorrect as it represents the factored form before cancellation. Choice D (1 + 2/x) is incorrect as it does not simplify the expression correctly.
Which of the following equations does not represent a function?
- A. y = x^2
- B. y = sqrt(x)
- C. x = y^2
- D. y = 2x + 1
Correct Answer: C
Rationale: An equation represents a function if each input (x-value) corresponds to exactly one output (y-value). In the equation x = y^2, for a single x-value, there are two possible y-values (positive and negative square root), violating the definition of a function. This violates the vertical line test, where a vertical line intersects the graph in more than one point for non-functions. Choices A, B, and D all pass the vertical line test and represent functions, making them incorrect answers.
What is the result of adding 7/8 and 5/8 and expressing the sum in reduced form?
- A. 9/17
- B. 1/3
- C. 31/36
- D. 3/5
Correct Answer: C
Rationale: To add 7/8 and 5/8, we combine the numerators while keeping the denominator the same: 7/8 + 5/8 = (7+5)/8 = 12/8. To simplify this fraction, we divide both the numerator and the denominator by their greatest common factor, which is 4. This yields 12/8 = 3/2. Therefore, the reduced form of 7/8 + 5/8 is 3/2, which is also equivalent to 1.5 as a mixed number. However, the question specifically asks for the answer in reduced form, making choice C, 3/2 or 31/36 after further simplification, the correct answer. Choices A, B, and D are incorrect because they do not represent the correct result of adding 7/8 and 5/8 in reduced form.