<PRE><B>Question 897087</B>
The circumference is:
{{{ pi*d = 3.141*28 }}}
{{{ pi*d = 87.948 }}} in
One circumference is traced out in one revolution
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In words:
( revolutions / minute ) x ( inches / revolution ) = inches / minute
( revolutions / minute ) = ( inches / minute ) / ( inches / revolution ) 
( revolutions / minute ) = ( inches / minute ) / 87.948 
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( inches / minute ) = ( inches / feet ) x ( feet / mile ) x ( miles / hour ) x ( hours / minute )
( inches / minute ) = {{{ ( 12/1 )*( 5280/1 )*20*( 1/60 ) }}}
( inches / minute ) = {{{ 21120 }}}
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( revolutions / minute ) = {{{ 21120 / 87.948 }}}
{{{ 21120 / 87.948 = 240.1419 }}}
The tire makes 240.14 RPM
Hope I got it
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