math
posted by sarah .
a gardener places lilies in a pond.He does on the first day of the month of september.it double in volume every day until the last day of the month,the pool is full.On what day of the month was the pool half full of lilies?

It will be half full of lilies in the second to the last day of the month.

is it day 20,or day 15

Neither.
It's half full on September 29.
Remember the lilies double every day. 
It will be the last day....
Remember Ms. Sue, Friday, March 1, 2013 at 9:22pm "Remember the lilies double every day" So the previous day would be half the amount.