NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 12: Surface Areas & Volumes - Exercise 12.2
Question 4

Question. 4

A solid ball is exactly fitted inside the cubical box of side \(a\). The volume of the ball is \(\dfrac{4}{3}\pi a^3\).

Answer:

false

Detailed Answer with Explanation:

Step 1: The ball fits exactly inside the cube. This means the diameter of the ball is equal to the side of the cube. So, diameter of ball = \(a\) (in metres, SI unit).

Step 2: Radius is half of diameter. Therefore, radius \(r = \dfrac{a}{2}\, \text{m}\).

Step 3: Formula for volume of a sphere (ball) is: \[ V = \dfrac{4}{3} \pi r^3 \]

Step 4: Substitute \(r = a/2\): \[ V = \dfrac{4}{3} \pi \left(\dfrac{a}{2}\right)^3 = \dfrac{4}{3} \pi \cdot \dfrac{a^3}{8} = \dfrac{\pi a^3}{6} \]

Step 5: The question states that the volume is \(\dfrac{4}{3}\pi a^3\). But we found the actual volume is \(\dfrac{\pi a^3}{6}\).

Final Answer: Since the given volume is incorrect, the statement is False.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 12: Surface Areas & Volumes – Exercise 12.2 | Detailed Answers