If the length of a rectangle is increased by 30% and the width of the same rectangle is decreased by 30%, what is the effect on the area of the rectangle?
- A. It is increased by 60%.
- B. It is unchanged.
- C. It is decreased by 15%.
- D. It is decreased by 9%.
Correct Answer & Rationale
Correct Answer: D
Increasing the length of a rectangle by 30% results in a new length of 1.3L, while decreasing the width by 30% gives a new width of 0.7W. The new area can be calculated as A' = (1.3L)(0.7W) = 0.91LW, indicating a decrease in area. Option A is incorrect because a 60% increase does not occur; the area actually decreases. Option B is wrong as the area changes due to the modifications in dimensions. Option C suggests a decrease of 15%, which miscalculates the area change. The area decreases by 9%, confirming the effect of the opposing percentage changes in length and width.
Increasing the length of a rectangle by 30% results in a new length of 1.3L, while decreasing the width by 30% gives a new width of 0.7W. The new area can be calculated as A' = (1.3L)(0.7W) = 0.91LW, indicating a decrease in area. Option A is incorrect because a 60% increase does not occur; the area actually decreases. Option B is wrong as the area changes due to the modifications in dimensions. Option C suggests a decrease of 15%, which miscalculates the area change. The area decreases by 9%, confirming the effect of the opposing percentage changes in length and width.
Other Related Questions
0.034÷(10)^(-1) =
- A. 0.0034
- B. 0.034
- C. 0.34
- D. 3.4
Correct Answer & Rationale
Correct Answer: C
To solve 0.034 ÷ (10)^(-1), we first recognize that (10)^(-1) is equivalent to 1/10 or 0.1. Dividing by 0.1 is the same as multiplying by 10. Therefore, 0.034 ÷ 0.1 equals 0.034 × 10, which results in 0.34. Option A (0.0034) misinterprets the division, mistakenly moving the decimal too far left. Option B (0.034) fails to account for the division by 0.1, leaving the original number unchanged. Option D (3.4) incorrectly multiplies instead of dividing, moving the decimal point too far right. Thus, the only accurate calculation leads to 0.34.
To solve 0.034 ÷ (10)^(-1), we first recognize that (10)^(-1) is equivalent to 1/10 or 0.1. Dividing by 0.1 is the same as multiplying by 10. Therefore, 0.034 ÷ 0.1 equals 0.034 × 10, which results in 0.34. Option A (0.0034) misinterprets the division, mistakenly moving the decimal too far left. Option B (0.034) fails to account for the division by 0.1, leaving the original number unchanged. Option D (3.4) incorrectly multiplies instead of dividing, moving the decimal point too far right. Thus, the only accurate calculation leads to 0.34.
3√2- 2/(√2) =
- A. 2√2
- B. √2
- C. 3
- D. 4
Correct Answer & Rationale
Correct Answer: A
To solve the expression \( 3\sqrt{2} - \frac{2}{\sqrt{2}} \), we first simplify \( \frac{2}{\sqrt{2}} \). This can be rewritten as \( \frac{2\sqrt{2}}{2} = \sqrt{2} \). Thus, the expression becomes \( 3\sqrt{2} - \sqrt{2} \), which simplifies to \( 2\sqrt{2} \). Option B (\( \sqrt{2} \)) is incorrect as it does not account for the subtraction from \( 3\sqrt{2} \). Option C (3) is incorrect because it misrepresents the value obtained after simplification. Option D (4) is also incorrect, as it does not relate to the expression at all.
To solve the expression \( 3\sqrt{2} - \frac{2}{\sqrt{2}} \), we first simplify \( \frac{2}{\sqrt{2}} \). This can be rewritten as \( \frac{2\sqrt{2}}{2} = \sqrt{2} \). Thus, the expression becomes \( 3\sqrt{2} - \sqrt{2} \), which simplifies to \( 2\sqrt{2} \). Option B (\( \sqrt{2} \)) is incorrect as it does not account for the subtraction from \( 3\sqrt{2} \). Option C (3) is incorrect because it misrepresents the value obtained after simplification. Option D (4) is also incorrect, as it does not relate to the expression at all.
A salesperson's commission is k percent of the selling price of a car. Which of the following represents the commission, in dollars, on 2 cars that sold for $14,000 each?
- A. 280k
- B. 28,000k
- C. 14,000/(100+2k)
- D. (28,000+k)/100
Correct Answer & Rationale
Correct Answer: A
To determine the commission on 2 cars sold for $14,000 each, first calculate the total selling price: 2 × $14,000 = $28,000. The commission, being k percent of this total, is expressed as (k/100) × $28,000, which simplifies to $280k. Option B, 28,000k, incorrectly suggests the commission is k percent of the total without dividing by 100. Option C, 14,000/(100+2k), misrepresents the calculation entirely by altering the formula. Option D, (28,000+k)/100, incorrectly adds k to the total selling price before calculating the percentage, which is not aligned with commission calculation principles.
To determine the commission on 2 cars sold for $14,000 each, first calculate the total selling price: 2 × $14,000 = $28,000. The commission, being k percent of this total, is expressed as (k/100) × $28,000, which simplifies to $280k. Option B, 28,000k, incorrectly suggests the commission is k percent of the total without dividing by 100. Option C, 14,000/(100+2k), misrepresents the calculation entirely by altering the formula. Option D, (28,000+k)/100, incorrectly adds k to the total selling price before calculating the percentage, which is not aligned with commission calculation principles.
Lanelle traveled 9.7 miles of her delivery route in 1.2 hours. At this same rate, which of the following is closest to the time it will take for Janelle to travel 20 miles?
- A. 2 hours
- B. 2.5 hours
- C. 5 hours
- D. 5.5 hours
Correct Answer & Rationale
Correct Answer: B
To determine the time it will take for Janelle to travel 20 miles, we first calculate Lanelle's speed. She traveled 9.7 miles in 1.2 hours, giving a speed of approximately 8.08 miles per hour (9.7 miles ÷ 1.2 hours). Using this speed, we can find the time for 20 miles by dividing the distance by the speed: 20 miles ÷ 8.08 mph ≈ 2.48 hours, which rounds to about 2.5 hours. Option A (2 hours) underestimates the time based on Lanelle's speed. Options C (5 hours) and D (5.5 hours) greatly overestimate the time needed. Thus, 2.5 hours is the most accurate estimate for Janelle's travel time.
To determine the time it will take for Janelle to travel 20 miles, we first calculate Lanelle's speed. She traveled 9.7 miles in 1.2 hours, giving a speed of approximately 8.08 miles per hour (9.7 miles ÷ 1.2 hours). Using this speed, we can find the time for 20 miles by dividing the distance by the speed: 20 miles ÷ 8.08 mph ≈ 2.48 hours, which rounds to about 2.5 hours. Option A (2 hours) underestimates the time based on Lanelle's speed. Options C (5 hours) and D (5.5 hours) greatly overestimate the time needed. Thus, 2.5 hours is the most accurate estimate for Janelle's travel time.