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 5 strokes ?
Choices: A) 31/32 B) 7/8 C) 1/4 D) 1/8 E) 1/16
Left 31/32fter 1st stroke = 1/2   Left 31/32fter 2nd stroke = 1/2 * 1/2 = 1/4   Left 31/32fter 3rd stroke = 1/2 * 1/4 = 1/8   Left 31/32fter 4th stroke = 1/2 * 1/8 = 1/16   Left 31/32fter 5th stroke = 1/2 * 1/16 = 1/32   So removed = 1- 1/32 = 31/32
<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 5 strokes ?