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Translate the phrase 'Five less than twice the number' into a mathematical expression.
- A. 5x-2
- B. 2x-5
- C. 2-5x
- D. 5-2x
Correct Answer: B
Rationale: To translate 'Five less than twice the number' into a mathematical expression, you first calculate twice the number (2x) and then subtract 5 from it. This gives you 2x-5. Therefore, choice B, 2x-5, accurately represents the mathematical expression for 'Five less than twice the number.' The phrase 'Five less than' implies subtraction, and 'twice the number' is represented by 2x. Thus, when you subtract 5 from twice the number, the correct expression is 2x-5.
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What is the best decimal approximation of 10 times the positive square root of 20?
- A. 89.4
- B. 200
- C. 44.7
- D. 100
Correct Answer: C
Rationale: To find 10 times the positive square root of 20, first calculate the square root of 20, which is approximately 4.472. Then, multiply this by 10: 10 * 4.472 ≈ 44.7. The best decimal approximation of 10 times the positive square root of 20 is 44.7, which corresponds to Option C.
A bucket can hold 3L. How many milliliters can the bucket hold?
- A. 300ml
- B. 3000ml
- C. 0.003ml
- D. 30ml
Correct Answer: B
Rationale: To convert liters to milliliters, you need to multiply by 1000 since 1 liter is equal to 1000 milliliters. Therefore, to determine how many milliliters a 3-liter bucket can hold, you multiply 3 by 1000, resulting in 3000ml. Hence, a bucket that can hold 3L is capable of holding 3000ml.
A child has a bottle full of pennies, nickels, dimes, and quarters. There are twice as many quarters as pennies, four times as many nickels as pennies, and five times as many dimes as nickels. How many more dimes does the child have than quarters?
- A. 18 times as many
- B. 5 times as many
- C. 20 times as many
- D. 10 times as many
Correct Answer: A
Rationale: Let p be the number of pennies. Quarters = 2p, Nickels = 4p, Dimes = 5 * 4p = 20p. So, Dimes - Quarters = 20p - 2p = 18p. The child has 18 times more dimes than quarters.
2.50 × 0.25 Simplify the expression above. Which of the following is correct?
- A. 6.25
- B. 0.0625
- C. 6.025
- D. 0.625
Correct Answer: D
Rationale: Multiplying 2.50 by 0.25 gives 0.625.
How should the frequency for each day of the week that students get up after 8 a.m. be best displayed from a class survey?
- A. Bar graph
- B. Scatter plot
- C. Histogram
- D. Pie chart
Correct Answer: A
Rationale: A bar graph is the most appropriate way to display the frequency of students getting up after 8 a.m. on each day of the week. Bar graphs are well-suited for comparing discrete categories, making them ideal for showing the frequency distribution of responses for each day. Each day of the week can be represented on the x-axis, and the frequency of students getting up after 8 a.m. on the y-axis. This allows for a clear visual comparison between the days, making it easy to see which days have a higher frequency of students waking up after 8 a.m. In this case, a bar graph is preferred over other options like scatter plots, histograms, or pie charts, as it provides a simple and effective way to visualize and compare the data across different days of the week.