<span>2/5 is close to 1/2, and it is easy to find 1/2 of 7 mentally. Half of 7 is 3.5, so Martin gave away about 3.5 pounds.</span>
Answer:
Option (4).
Step-by-step explanation:
Outer diameter of the hollow metallic ball = 10 centimeters
Outer radius of this ball =
= 5 cm
Volume of the outer ball
= 
= 
Inner radius of the hollow metallic ball = (5 - 1) = 4 cm
Volume of the inner hollow ball
= 
Volume of the metal used in the metallic ball = 
= 
= ![\frac{4}{3}\pi [(5)^3-(4)^3]](https://tex.z-dn.net/?f=%5Cfrac%7B4%7D%7B3%7D%5Cpi%20%5B%285%29%5E3-%284%29%5E3%5D)
Therefore, expression given in option (4) will be used to measure the volume of the hollow metallic ball.
I have the best ans and that is