Sean was playing with his bubble wand. His bubble wand could eject 100 bubbles at once. Half of the bubbles would burst within one minute. 1/4 of the original number of the bubbles would survive for 2 minutes. Only 2% of the original number of bubbles would make it to the end of 3 minutes. All the bubbles would burst at the 4th minute. If Sean blew the bubble wand every minute, how many bubbles were there altogether at the 10th minutes?
after one minute 50 left
after 2 minutes 25 bubbles left
after 3 minutes 2 bubles left
after 4 minutes 0 bubles left
the question is unclear as to whether the bubbles are blown at the end or at the beginning of each minute.
Let's say they are blown at the end of each minute.
So at (immediately after) the end of ten minutes there are
100 bubbles that have just been blown
+ 50 that were blown a minute ago
+ 25 that were blown 2 minutes ago
+ 2 that were blown 3 minutes ago
and all the ones that were blown before that are gone.
You can add them up :)