A study found that athletes who rested after exhausting exercise had half life of lactic acid removal about 23 minutes. How long would it take to remove 90% of the lactic acid?
amount = (1/2)^(t/23), where t is in minutes
.1 = (.5)^(t/23)
log both sides
log .1 = (t/23)log .5
t/23 = log.1/log.5
t = 23log.1/log.5 = appr 76.4 minutes
check:
after 23 minutes, 50% would be left
after 46 minutes, 25% would be left
after 69 minutes 12.5% would be left
my answer is quite reasonable