Math
posted by Diana on .
lisa checks the stats for her favorite puzzle game on her Ipod. she sees that she has won exactly 72% of the 2400 puzzles that she has played. what is the minimum numbers of puzzles that lisa must win before she has won at least 73% of the total number of puzzels played.
i tried many ways to figure this out and i keep gettin small decimals. can someone help me?

There is possibly an easier way to do this, but let me start off with this logic.
Let's find out how many games she won and lost. That will give us a little more information.
72\100 x 2400 = 1728. She won 1728 games, so she lost 672.
The thing we don't know yet is how many more games she will play. We know that each game will be win. We'll call each new game "n."
73% (2400 + n) = 1728 + n
1752 + .73n = 1728 + n
24 = .27n.
Take 24 divided by .27 to get n alone:
n = 88.8888
Since she cannot play .8888 games, we know she has to play 89 more. Let's check it.
2489 (the new number of games) x 73% = 1816.97 (or 1817...the new number of wins).
So she has to win 89 more games, which makes the total games won (which is how I read the question) 2489.