请教一道PS题

xingxc11

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 4 strokes?
答案是15/16 请大牛帮忙翻译一下此题

xingxc11

If1/2 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 4 strokes?
答案是15/16 请大牛帮忙翻译一下此题 (之前粘错了。。。）

tony249

Tank里的空气每次被抽掉一半(应该是剩下的一半)
求抽了四次后被抽掉的空气占原来的多少
(1/2 + 1/4 + 1/8 + 1/16) /1= 15/16