document.write( "Question 257443: Josh’s bicycle has 28-inch-diameter wheels and Julian’s has 14-inch-diameter wheels. Josh’s wheel rotates twice for every three rotations of the pedals; Julian’s wheel rotates three times for every two rotations of the pedals. Josh rotates the pedals twice as quickly as Julian (twice as many rotations per unit of time). Julian takes 8 minutes to bicycle one mile. How much time will Josh take? \n" ); document.write( "
Algebra.Com's Answer #189442 by CharlesG2(834)![]() ![]() ![]() You can put this solution on YOUR website! Josh’s bicycle has 28-inch-diameter wheels and Julian’s has 14-inch-diameter wheels. Josh’s wheel rotates twice for every three rotations of the pedals; Julian’s wheel rotates three times for every two rotations of the pedals. Josh rotates the pedals twice as quickly as Julian (twice as many rotations per unit of time). Julian takes 8 minutes to bicycle one mile. How much time will Josh take?\r \n" ); document.write( "\n" ); document.write( "(60 minutes in an hour) X (N revolutions per minute) X ((D wheel diameter in inches) X pi per revolution) DIVIDED BY (5280 feet in a mile) times (12 inches in a foot) = \n" ); document.write( "(speed in miles per hour) \n" ); document.write( "60*(min/hr)*N*(rev/min)*(D*pi)*(in/rev) DIVIDED BY 5280*(ft/mi)* 12 * in/ft \n" ); document.write( "60*N*D*pi*(in/hr) DIVIDED BY 5280*12*(in/mile) \n" ); document.write( "(60*N*D*pi)/(5280*12) miles/hr \n" ); document.write( "(5*N*D*pi)/5280 miles/hr (60/12=5) \n" ); document.write( "(N*D*pi)/1056 miles/hr (1056*5=5280)\r \n" ); document.write( "\n" ); document.write( "1 mile / 8 min * 60 minutes / 1 hr \n" ); document.write( "1/8 * (miles/min) * 60 * (min/hr) \n" ); document.write( "1/8 * 60 miles/hr \n" ); document.write( "7.5 miles/hr or 1/8 mile/min\r \n" ); document.write( "\n" ); document.write( "for Julian 7.5=(N*D*pi)/1056 \n" ); document.write( " 7920=N*D*pi \n" ); document.write( " 7920=N*14*pi \n" ); document.write( " 180.0724498983=N in rev/min \n" ); document.write( " 1440.5795991861 revolutions in 8 minutes \n" ); document.write( " 10804.3469938955 rev/hr (60 min/hr)\r \n" ); document.write( "\n" ); document.write( "Josh’s wheel rotates twice for every three rotations of the pedals; Julian's wheel rotates three times for every two rotations of the pedals. Josh rotates the pedals twice as quickly as Julian\r \n" ); document.write( "\n" ); document.write( "2 rev / 3 pedal or 2/3 rev per pedal or 2/3*28*pi inches per pedal \n" ); document.write( " 58.643062867 inches per pedal \n" ); document.write( "3 rev / 2 pedal or 3/2 rev per pedal or 3/2*14*pi inches per pedal \n" ); document.write( " 65.9734457254 inches per pedal \n" ); document.write( "and Josh pedals twice as fast so Josh covers 117.286125734 inches in same time it takes Julian to go 65.9734457254 inches \n" ); document.write( "a ratio of 1.7777777778 to 1\r \n" ); document.write( "\n" ); document.write( "8 minutes / 1.7777777778 = 4.4999999999 = 4.5\r \n" ); document.write( "\n" ); document.write( "Josh will take 4.5 minutes\r \n" ); document.write( "\n" ); document.write( " \r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |