Sainik School Entrance Exam 2019 Solved Paper

Question : 47 of 150

Marks: +1, -0

A solid gold ball of radius

7 {\cm}

was melted and then drawn into a wire of diameter

0.2 {\cm}

. Find the length of the wire.

Solution:

(a) Suppose the length of the wire

=l {\cm}

Volume of ball = Volume of the wire

π(0.1)^2 \times l={4}/{3} π(7)^3

l={4 ×7 ×7 ×7}/{3 ×0.1 ×0.1}

l=45733 {\cm}=457.33 .....[ ∵1 {\m}=100 {\cm}]

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