Multiple choice

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 will be left in the tank after 4 strokes?

  1. 1/16

  2. 7/8

  3. 1/4

  4. 1/8

  5. 15/16
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A Correct answer
Explanation

Each stroke removes 1/2, leaving 1/2. After 4 strokes, the remaining fraction is (1/2)^4 = 1/16.

AI explanation

Since half of the air is removed with each stroke, the remaining air after each stroke is multiplied by 1/2. Using the formula for repeated replacement, the fraction of air left after 4 strokes is (1/2)^4. Calculating 1/2 multiplied by itself four times gives 1/16.

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