Nokea
Jessica buys 10 cans of paint. Red paint costs $1 per can, and blue paint costs $2 per can. In total, she spends $16. How many red cans did she buy?
- A. 2
- B. 3
- C. 4
- D. 5
Correct Answer: C
Rationale: Let r be the number of red cans and b be the number of blue cans. The total cans equation is r + b = 10. The total cost equation is r + 2b = 16. By solving these equations simultaneously, we find r = 4. Therefore, Jessica bought 4 red cans. Choice A, 2 red cans, is incorrect because it does not satisfy the total cans or total cost condition. Choices B and D are also incorrect as they do not fulfill both conditions simultaneously.
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Your measurement of the width of a door is 36 inches. The actual width of the door is 35.75 inches. What is the relative error in your measurement?
- A. 0.70%
- B. 0.01%
- C. 0.99%
- D. 0.10%
Correct Answer: A
Rationale: To calculate relative error, you use the formula: (|measured value - actual value| / actual value) * 100%. Substituting the values, we get (|36 - 35.75| / 35.75) * 100% = (0.25 / 35.75) * 100% = 0.7%. This means your measurement is off by 0.7% from the actual width of the door. Choice B, 0.01%, is too small as it doesn't reflect the actual difference. Choices C and D are significantly different from the calculated answer and do not represent the accurate relative error in the measurement.
What is 1.25 as a fraction?
- A. 1 1/4
- B. 5/4
- C. 4/5
- D. 25/20
Correct Answer: B
Rationale: To convert a decimal to a fraction, we note that 1.25 can be expressed as 1 + 0.25. Since 0.25 is equivalent to 25/100 or 1/4, we add 1 whole to 1/4 to get 1 1/4, which simplifies to 5/4. Therefore, 1.25 as a fraction is 5/4. Choice A (1 1/4) is the mixed number form of 5/4. Choice C (4/5) and Choice D (25/20) are incorrect fractions that do not represent 1.25.
What is the area of a rectangle with a length of 5 cm and a width of 4 cm?
- A. 9 cm²
- B. 20 cm²
- C. 10 cm²
- D. 25 cm²
Correct Answer: B
Rationale: To find the area of a rectangle, you multiply its length by its width. In this case, the length is 5 cm and the width is 4 cm. So, Area = length * width = 5 cm * 4 cm = 20 cm². Therefore, the correct answer is 20 cm². Choice A (9 cm²), Choice C (10 cm²), and Choice D (25 cm²) are incorrect as they do not result from the correct calculation of multiplying the length and width of the rectangle.
Shawna buys 5 gallons of paint. If she uses 2/5 of it on the first day, how much paint does she have left?
- A. 3 gallons
- B. 2 gallons
- C. 1 gallon
- D. 0.5 gallons
Correct Answer: A
Rationale: To find out how much paint Shawna uses on the first day, calculate 2/5 * 5 = 2 gallons. Subtracting the amount used from the total amount gives us 5 - 2 = 3 gallons remaining. Therefore, Shawna has 3 gallons of paint left after using 2 gallons on the first day. Choice A is correct. Choices B, C, and D are incorrect because she has more paint left than the options presented.
What is the value of the sum of 3/4 and 5/8?
- A. 1 3/8
- B. 1 1/2
- C. 1 7/8
- D. 1 5/8
Correct Answer: D
Rationale: To find the sum of fractions, they need to have a common denominator. In this case, the common denominator is 8. So, 3/4 = 6/8. Adding 6/8 and 5/8 gives 11/8, which simplifies to 1 3/8. Therefore, the correct answer is 1 3/8, which corresponds to choice A. Choices B, C, and D are incorrect as they do not represent the correct sum of 3/4 and 5/8.