SOLUTION: A swimming pool of 1 million gallons of water loses 7% daily. How many days will it take before there is only 10% or less water left in the pool.

Question 1020588: A swimming pool of 1 million gallons of water loses 7% daily. How many days will it take before there is only 10% or less water left in the pool.
Found 3 solutions by josgarithmetic, robertb, josmiceli:
Answer by josgarithmetic(39614)   (Show Source): You can put this solution on YOUR website!
The pool KEEPS 93% daily.

When is v=100000 gallons?

, best to call this .
Answer by robertb(5830)   (Show Source): You can put this solution on YOUR website!
The remaining amount of water in the swimming pool is modeled by the geometric expression
, or .
We want this expression to be less than or equal to 10% of 1,000,000, or 10^6, gallons of water, which is 10^5 gallons. Hence

==>
Applying logs (base 10) to both sides, we get

==> (the direction of the inequality is reversed because log0.93 is negative.)
Therefore on and after 31.73 days, there is 10% or less water remaining in the pool.

Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
day# - - - factor times
-------------------------------
1 - - -
2 - - -
2 - - -
The rule is:
n - - -
-------------------------------
The remaining water after days is:

You are given that:

Divide both sides by

Take log base 10 of both sides

I can round this off to 32 days until the
water left in the pool is 10% or less
----------------------------------
check:

close enough
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