P=2(L+W), P=48, W=L-4. Width?
- A. 10
- B. 12
- C. 20
- D. 24
Correct Answer & Rationale
Correct Answer: A
To find the width (W), start with the given perimeter formula \( P = 2(L + W) \). Substituting \( P = 48 \) gives \( 48 = 2(L + W) \), which simplifies to \( L + W = 24 \). Given \( W = L - 4 \), substitute this into the equation: \( L + (L - 4) = 24 \). This simplifies to \( 2L - 4 = 24 \), leading to \( 2L = 28 \) and \( L = 14 \). Thus, \( W = 14 - 4 = 10 \). Option B (12) does not satisfy the perimeter equation. Option C (20) and Option D (24) also do not fit the derived equations, confirming that W must be 10.
To find the width (W), start with the given perimeter formula \( P = 2(L + W) \). Substituting \( P = 48 \) gives \( 48 = 2(L + W) \), which simplifies to \( L + W = 24 \). Given \( W = L - 4 \), substitute this into the equation: \( L + (L - 4) = 24 \). This simplifies to \( 2L - 4 = 24 \), leading to \( 2L = 28 \) and \( L = 14 \). Thus, \( W = 14 - 4 = 10 \). Option B (12) does not satisfy the perimeter equation. Option C (20) and Option D (24) also do not fit the derived equations, confirming that W must be 10.
Other Related Questions
1.085/12 value?
- A. 90
- B. 90 * 5/1.085
- C. 90 * 5/12
- D. 90.5
Correct Answer & Rationale
Correct Answer: C
To find the value of 1.085/12, we need to simplify the expression. Option C, 90 * 5/12, correctly represents a simplified fraction of 90 divided by 12, multiplied by 5. This yields a value consistent with the original division. Option A (90) is incorrect as it does not involve the division by 12. Option B (90 * 5/1.085) incorrectly uses 1.085 as a divisor instead of 12, leading to an inaccurate calculation. Option D (90.5) is also incorrect as it does not relate to the division of 1.085 by 12, resulting in a value that does not reflect the operation required.
To find the value of 1.085/12, we need to simplify the expression. Option C, 90 * 5/12, correctly represents a simplified fraction of 90 divided by 12, multiplied by 5. This yields a value consistent with the original division. Option A (90) is incorrect as it does not involve the division by 12. Option B (90 * 5/1.085) incorrectly uses 1.085 as a divisor instead of 12, leading to an inaccurate calculation. Option D (90.5) is also incorrect as it does not relate to the division of 1.085 by 12, resulting in a value that does not reflect the operation required.
Quickly multiply 24x16?
- A. 20x20-4x4
- B. 20x20
- C. 20x10+4x6
- D. 25x10+4x15
Correct Answer & Rationale
Correct Answer: A
Option A, 20x20 - 4x4, effectively utilizes the difference of squares method. It simplifies the multiplication by recognizing that 24 can be expressed as 20 + 4 and 16 as 20 - 4, leading to a calculation of (20+4)(20-4). Option B, 20x20, underestimates the value of 24 and 16, yielding only 400 instead of the correct 384. Option C, 20x10 + 4x6, inaccurately breaks down the multiplication, leading to 200 + 24, which totals 224. Option D, 25x10 + 4x15, misrepresents the factors, resulting in 250 + 60, totaling 310. Thus, option A is the most accurate approach for this multiplication.
Option A, 20x20 - 4x4, effectively utilizes the difference of squares method. It simplifies the multiplication by recognizing that 24 can be expressed as 20 + 4 and 16 as 20 - 4, leading to a calculation of (20+4)(20-4). Option B, 20x20, underestimates the value of 24 and 16, yielding only 400 instead of the correct 384. Option C, 20x10 + 4x6, inaccurately breaks down the multiplication, leading to 200 + 24, which totals 224. Option D, 25x10 + 4x15, misrepresents the factors, resulting in 250 + 60, totaling 310. Thus, option A is the most accurate approach for this multiplication.
Caterpillar 1 ft in 7.5 min. 18 min?
- A. 2.4
- B. 8
- C. 11.5
- D. 25.5
Correct Answer & Rationale
Correct Answer: A
To determine how far the caterpillar travels in 18 minutes, first calculate its speed. It moves 1 foot in 7.5 minutes, which equates to \( \frac{1 \text{ ft}}{7.5 \text{ min}} \). In 18 minutes, the distance covered can be calculated using the formula: \[ \text{Distance} = \text{Speed} \times \text{Time} \] Converting 18 minutes into feet: \[ \text{Distance} = \left(\frac{1 \text{ ft}}{7.5 \text{ min}}\right) \times 18 \text{ min} = 2.4 \text{ ft} \] Option B (8) overestimates the distance, while C (11.5) and D (25.5) significantly exceed the calculated distance, demonstrating a misunderstanding of the speed-time relationship.
To determine how far the caterpillar travels in 18 minutes, first calculate its speed. It moves 1 foot in 7.5 minutes, which equates to \( \frac{1 \text{ ft}}{7.5 \text{ min}} \). In 18 minutes, the distance covered can be calculated using the formula: \[ \text{Distance} = \text{Speed} \times \text{Time} \] Converting 18 minutes into feet: \[ \text{Distance} = \left(\frac{1 \text{ ft}}{7.5 \text{ min}}\right) \times 18 \text{ min} = 2.4 \text{ ft} \] Option B (8) overestimates the distance, while C (11.5) and D (25.5) significantly exceed the calculated distance, demonstrating a misunderstanding of the speed-time relationship.
Prism: 5.0cm, 7.3cm, 9.2cm. Surface area?
- A. 149.66
- B. 167.9
- C. 299.32
- D. 335.18
Correct Answer & Rationale
Correct Answer: C
To find the surface area of a rectangular prism, the formula is SA = 2(lw + lh + wh), where l, w, and h are the length, width, and height, respectively. Substituting the given dimensions (5.0 cm, 7.3 cm, and 9.2 cm) into the formula yields a surface area of 299.32 cm². Option A (149.66) likely results from miscalculating or omitting a dimension. Option B (167.9) may arise from incorrect multiplication or addition. Option D (335.18) could be a result of doubling the correct surface area without proper calculation. Thus, only option C accurately represents the surface area of the prism.
To find the surface area of a rectangular prism, the formula is SA = 2(lw + lh + wh), where l, w, and h are the length, width, and height, respectively. Substituting the given dimensions (5.0 cm, 7.3 cm, and 9.2 cm) into the formula yields a surface area of 299.32 cm². Option A (149.66) likely results from miscalculating or omitting a dimension. Option B (167.9) may arise from incorrect multiplication or addition. Option D (335.18) could be a result of doubling the correct surface area without proper calculation. Thus, only option C accurately represents the surface area of the prism.