If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 6 strokes ? Choose the correct option.
A) 63/64 B) 7/8 C) 1/4 D) 1/8 E) 1/16
Left 63/64fter 1st stroke = 1/2   Left 63/64fter 2nd stroke = 1/2 * 1/2 = 1/4   Left 63/64fter 3rd stroke = 1/2 * 1/4 = 1/8   Left 63/64fter 4th stroke = 1/2 * 1/8 = 1/16   Left 63/64fter 5th stroke = 1/2 * 1/16 = 1/32   Left 63/64fter 6th stroke = 1/2 * 1/32 = 1/64   So removed = 1- 1/64 = 63/64
<result>A</result>
If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 6 strokes ?