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After 1st stroke, 5/6 of the initial air mass remains;
After 2nd stroke, of the initial air mass remains;
After 3rd stroke, of the initial air mass remains;
After 4th stroke, of the initial air mass remains;
After 5th stroke, of the initial air mass remains;
After 6th stroke, of the initial air mass remains, or 0.3349 of the initial air mass remains (rounded). ANSWER
Solved.
For similar (TWIN) solved problems, see the links
https://www.algebra.com/algebra/homework/word/misc/Miscellaneous_Word_Problems.faq.question.1097807.html
https://www.algebra.com/algebra/homework/Sequences-and-series/Sequences-and-series.faq.question.75801.html
at this forum.
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Regarding the post by @MathLover1, I recall this medical proverb:
a drop of nicotine kills a horse.
Likewise, @MatnLover1's answer may kill a reader.
He will die if not from horror to have such a " tutor ", then from laughter.
So, for safety of your mind, you better ignore her post.