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A lab technician took 100 hairs from a patient to conduct several tests. The technician used 1/7 of the hairs for a drug test. How many hairs were used for the drug test? (Round your answer to the nearest hundredth.)
- A. 14
- B. 14.2
- C. 14.29
- D. 14.3
Correct Answer: C
Rationale: To find how many hairs were used for the drug test, you need to calculate 1/7 of 100. 1/7 of 100 is 14.2857, which rounds to 14.29 when rounded to the nearest hundredth. Therefore, 14.29 hairs were used for the drug test. Choice A is incorrect as it does not account for rounding to the nearest hundredth. Choices B and D are incorrect as they do not accurately reflect the calculated value after rounding.
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How many centimeters are in 7 meters?
- A. 7 m = 7 cm
- B. 7 m = 70 cm
- C. 7 m = 700 cm
- D. 7 m = 7000 cm
Correct Answer: C
Rationale: The prefix 'centi-' means one-hundredth. In the metric system, 1 meter is equal to 100 centimeters. Therefore, to convert meters to centimeters, you multiply the number of meters by 100. In this case, 7 meters is equal to 7 * 100 = 700 centimeters. Choice A is incorrect as it does not consider the conversion factor properly. Choice B is incorrect as it only accounts for a factor of 10 instead of 100. Choice D is incorrect as it overestimates the conversion by a factor of 10.
What was the mean time for the women who ran the 200m event at the 2008 Olympic Games (times in seconds: 22.33, 22.50, 22.50, 22.61, 22.71, 22.72, 22.83, 23.22)?
- A. 22.50 sec
- B. 22.66 sec
- C. 22.68 sec
- D. 22.77 sec
Correct Answer: C
Rationale: To find the mean time, you need to add all the times (22.33 + 22.50 + 22.50 + 22.61 + 22.71 + 22.72 + 22.83 + 23.22) and then divide by the total number of times (8). This calculation results in a mean time of 22.68 seconds. Choice A, 22.50 sec, is incorrect because it is the time of one of the runners, not the mean time. Choice B, 22.66 sec, and Choice D, 22.77 sec, are also incorrect as they are not the calculated mean of the given times.
Solve for x: 3(x - 1) = 2(3x - 9)
- A. x = 2
- B. x = 8/3
- C. x = -5
- D. x = 5
Correct Answer: D
Rationale: To solve the equation 3(x - 1) = 2(3x - 9), first distribute and simplify both sides to get 3x - 3 = 6x - 18. Next, subtract 3x from both sides to get -3 = 3x - 18. Then, add 18 to both sides to obtain 15 = 3x. Finally, divide by 3 to find x = 5. Therefore, the correct answer is x = 5. Choices A, B, and C are incorrect because they do not represent the correct solution to the given equation after proper algebraic manipulation.
The table below shows the number of books checked out from a library over the course of 4 weeks. Which equation describes the relationship between the number of books (b) and weeks (w)?
- A. b = 10w + 2
- B. b = 5w + 10
- C. b = 8w + 12
- D. b = 4w + 20
Correct Answer: B
Rationale: The relationship between the number of books and weeks is best described by the equation b = 5w + 10. This is because the initial value of books checked out is 10, which indicates that even with 0 weeks, there are already 10 books checked out. The rate at which books are checked out per week is 5, as indicated by the coefficient of w. Therefore, the correct equation should be b = 5w + 10. Choices A, C, and D are incorrect because they do not represent the correct initial value or rate of increase for the given scenario.
Solve for x: 2x - 7 = 3
- A. x = 4
- B. x = 3
- C. x = -2
- D. x = 5
Correct Answer: D
Rationale: To solve the equation for x, follow these steps: 2x - 7 = 3. Add 7 to both sides to isolate 2x, resulting in 2x = 10. Then, divide by 2 on both sides to find x, which gives x = 5. Therefore, the correct answer is x = 5. Choices A, B, and C are incorrect because they do not accurately solve the equation.