Express the ratio of 6:7 as a percentage.
- A. 67%
- B. 76%
- C. 86%
- D. 93%
Correct Answer: A
Rationale: To express the ratio 6:7 as a percentage, we first need to find the total parts in the ratio, which is 6 + 7 = 13. To convert this ratio to a percentage, divide the part you want to find the percentage for by the total parts, then multiply by 100. In this case, to find the percentage for 6 in the ratio 6:7, the calculation would be (6/13) * 100 = 46.15%. Therefore, the correct answer is A, 67%. Choices B, C, and D are incorrect percentages as they do not result from the correct calculation for the given ratio.
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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 =
Rebecca is able to paint 12 pickets on her picket fence in an hour. Her fence is 72 feet long, with 2 pickets per foot. How long will it take her to paint the fence?
- A. 2.4 hours
- B. 6 hours
- C. 12 hours
- D. 16.4 hours
Correct Answer: B
Rationale: Rebecca can paint 12 pickets in 1 hour, which means she can paint 12 * 2 = 24 pickets in an hour. Since the fence is 72 feet long with 2 pickets per foot, she needs to paint a total of 72 * 2 = 144 pickets. If she paints 24 pickets per hour, it will take her 144 / 24 = 6 hours to paint the entire fence. Choice A (2.4 hours) is incorrect because it does not consider the total number of pickets on the fence. Choice C (12 hours) is incorrect as it overestimates the time needed based on her painting rate. Choice D (16.4 hours) is incorrect as it miscalculates the time required to paint the entire fence.
A cake recipe calls for 2½ cups of flour. How many cups are needed to make 6 cakes?
- A. 12.5 cups
- B. 13 cups
- C. 14 cups
- D. 15 cups
Correct Answer: D
Rationale: To make one cake, you need 2½ cups of flour. To make 6 cakes, you would need 6 times the amount of flour for one cake, which is 2½ x 6 = 15 cups. Therefore, the correct answer is 15 cups. Choices A, B, and C are incorrect as they do not correctly calculate the total amount of flour needed for 6 cakes.
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
Rationale: After spending $6.50 on a sandwich, the man had $3.50 left. Then, after spending $1.80 on a drink, he had $1.70 left. Finally, he spent another $0.75 on a bag of chips. Subtracting $0.75 from $1.70 gives us $0.95, which is the amount of money he had left. Choice A is incorrect because it does not consider the bag of chips he bought. Choice C is incorrect as it miscalculates the remaining amount. Choice D is incorrect as it does not account for the total expenses.
Convert this military time to regular time: 2120 hours.
- A. 9:20 A.M.
- B. 9:20 P.M.
- C. 2:12 A.M.
- D. 2:12 P.M.
Correct Answer: B
Rationale: To convert military time to regular time, subtract 12 from the hours if the time is in the afternoon or evening. In this case, 21 - 12 = 9, so 2120 hours is equivalent to 9:20 P.M. Therefore, the correct answer is option B, 9:20 P.M. Choices A, C, and D are incorrect because they do not correctly adjust the military time to regular time format. Choice A shows 9:20 A.M., which is incorrect as the time is in the evening. Choices C and D show times that are not derived from the given military time, making them incorrect as well.