Question
CBSEENMA9003528

Coins of same size are placed one above the other and a cylindrical solid block is formed. The volume of this block is 49.28 cm3. Diameter of each coin is 2.8 cm and thickness 0.2 cm. Find the number of coins arranged in the block.

open parentheses straight pi equals 22 over 7 close parentheses

Solution

Let n be the number of coins.

For block
straight r equals fraction numerator 2.8 over denominator 2 end fraction space cm equals 1.4 space cm
straight h equals space left parenthesis 0.2 right parenthesis straight n space cm
straight V equals 49.28 space cm cubed
rightwards double arrow space space space space 49.28 space equals space 22 over 7 left parenthesis 1.4 right parenthesis squared space left parenthesis 0.2 right parenthesis straight n
rightwards double arrow space space space straight n equals 40

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