Read the information given carefully and answer the question that follows:
(A) 72 kmph = 20 m/s
(B) 25 m/s = 80 kmph
(C) Total Surface area of a Cube of edge length a is $6a^2$
(D) Volume of a Cube of edge length a is $a^3$
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (C) & (D) only
Analysis of Statements
(A) 72 kmph = 20 m/s
To convert $km/h$ to $m/s$, multiply by $\frac{5}{18}$:
$72 \times \frac{5}{18} = 4 \times 5 = 20 \text{ m/s}$.
Statement (A) is CORRECT.
(B) 25 m/s = 80 kmph
To convert $m/s$ to $km/h$, multiply by $\frac{18}{5}$:
$25 \times \frac{18}{5} = 5 \times 18 = 90 \text{ km/h}$.
Statement (B) is INCORRECT.
(C) Total Surface area of a Cube of edge length a is $6a^2$
A cube has 6 faces, and the area of each face is $a^2$. Therefore, the total surface area is $6a^2$.
Statement (C) is CORRECT.
(D) Volume of a Cube of edge length a is $a^3$
The volume of a cube is calculated as $\text{length} \times \text{width} \times \text{height}$, which is $a \times a \times a = a^3$.
Statement (D) is CORRECT.
Conclusion
Statements (A), (C), and (D) are mathematically correct.