Posted by David on Tuesday, August 28, 2012 at 6:58pm.
Find the halflife (in hours) of a radioactive substance that is reduced by 10 percent in 5 hours.

Math  bobpursley, Tuesday, August 28, 2012 at 7:04pm
.6=e^.603 (5sec/th)
solve for thalflife.
ln.6=.693*5/th
th=???