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A lab needs 200ml of a 5% salt solution. They only have a 10% solution. How much 10% solution and water should be mixed?
- A. 100ml 10% solution, 100ml water
- B. 150ml 10% solution, 50ml water
- C. 160ml 10% solution, 40ml water
- D. 200ml 10% solution, 0ml water
Correct Answer: B
Rationale: Rationale:
1. Let x be the volume of the 10% solution needed and y be the volume of water needed.
2. The total volume of the final solution is 200ml, so x + y = 200.
3. The concentration of the final solution is 5%, so the amount of salt in the final solution is 0.05 * 200 = 10g.
4. The amount of salt in the 10% solution is 0.1x, and the amount of salt in the water is 0, so the total amount of salt in the final solution is 0.1x.
5. Since the total amount of salt in the final solution is 10g, we have 0.1x = 10.
6. Solving for x, we get x = 100ml.
7. Substituting x =
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- A. 0.5 liters
- B. 5 liters
- C. 50 liters
- D. 500,000 liters
Correct Answer: A
Rationale: The correct answer is A: 0.5 liters. To convert milliliters to liters, you need to divide by 1000 since there are 1000 milliliters in 1 liter. Therefore, 500 milliliters is equal to 0.5 liters. Choice B, 5 liters, is incorrect because it would be the equivalent of 5000 milliliters. Choice C, 50 liters, is incorrect as it is ten times the converted value. Choice D, 500,000 liters, is way off as it is a thousand times more than the correct conversion.
A bag contains 5 red marbles and 7 blue marbles. If you draw a marble without looking, what is the probability it will be red?
- A. 1/4
- B. 1/3
- C. 1/2
- D. 2/3
Correct Answer: B
Rationale: The total number of marbles in the bag is 5 (red) + 7 (blue) = 12 marbles. The probability of drawing a red marble is the number of red marbles divided by the total number of marbles: 5/12. Simplifying 5/12 gives 1/3. Therefore, the correct probability of drawing a red marble is 1/3. Choice A (1/4) is incorrect because there are more red marbles than 1/4 of the total marbles. Choice C (1/2) is incorrect as it represents half of the total marbles. Choice D (2/3) is incorrect as it implies there are more red marbles than there actually are.
A plan for a shed is drawn on a 1:10 scale. If the roof of the real shed measures 4 feet by 5 feet, what were the measurements on the plan?
- A. 80 inches by 100 inches
- B. 40 inches by 50 inches
- C. 4.8 inches by 6 inches
- D. 4 inches by 5 inches
Correct Answer: B
Rationale: When the real shed roof measures 4 feet by 5 feet, on a 1:10 scale plan, the measurements on the plan would be 1/10 of the real measurements. Therefore, the correct answer is 40 inches by 50 inches since it represents 1/10 of 4 feet by 5 feet. Choice A (80 inches by 100 inches) is incorrect because it is equivalent to the real shed measurements, not the scaled plan. Choice C (4.8 inches by 6 inches) is incorrect as it does not reflect the 1:10 scale reduction. Choice D (4 inches by 5 inches) is incorrect because it does not consider the scale factor of 1:10.
Subtract and simplify: -5 - (-6) =
- A. ½
- B. 1⅜
- C. 1
- D. 1â…”
Correct Answer: C
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After spending money on a sandwich, a drink, and a bag of chips, how much money did the man have left from his initial $10?
- A. $1.50
- B. $0.95
- C. $1.90
- D. $2.10
Correct Answer: B
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