A hollow spherical metallic ball has an external diameter 6 cm and is 1/2 cm thick. The volume of metal used in the metal is:  Choose the correct choice: A) 47 1/5cm3 B) 47 3/5cm3 C) 47 7/5cm3 D) 47 9/5cm3 E) None of these
Explanation:   Please note we are talking about "Hollow" ball. Do not ignore this word in this type of question in a hurry to solve this question.   If we are given with external radius and thickness, we can get the internal radius by subtracting them. Then the volume of metal can be obtained by its formula as,   External radius = 3 cm,   Internal radius = (3-0.5)= 
<gadget id="calculator">(3-0.5)</gadget>
<output>2.5</output>
2.5 cm   Volume of sphere=4/3πr3   =4/3∗22/7∗[3(2)−2.52]cm3   =4/3∗22/7∗91/8cm3   =143/3cm3=47 2/3cm3   Option 47 3/5cm3
<result>B</result>
A hollow spherical metallic ball has an external diameter 6 cm and is 1/2 cm thick. The volume of metal used in the metal is: