Question 641161
Looking just at the units:
( yards / sec )*( ft / yd )*( miles / ft )*( sec / min )*( min / hr ) = miles / hr
Now fill in the conversions
( 3 yards / sec )*( 3 ft / yd )*( mile / 5,280 ft )*( 60 sec / min )*( 60 min / hr ) = miles / hr
{{{ 3*3*( 1 / 5280 )*60*60 =  9*3600 *( 1 / 5280 ) }}}
{{{  32400 / 5280 = 6.136 }}}
Charlie runs 6.136 mi/hr