# Suppose the half life of element K is 20 minutes. If you have 200 g sample of K, how much of element K will be left after 60 minutes?

##### 1 Answer

Mar 31, 2016

#### Explanation:

Recall that the formula for half-life is:

#color(blue)(|bar(ul(color(white)(a/a)y=a(b)^(t/h)color(white)(a/a)|)))# where:

#y=# final amount

#a=# inital amount

#b=# growth/decay

#t=# time elapsed

#h=# half-life

To find the amount of the sample left after

#y=200(1/2)^(60/20)#

Solve for

#y=200(1/2)^3#

#y=200(1/8)#

#color(green)(|bar(ul(color(white)(a/a)y=25color(white)(i)gcolor(white)(a/a)|)))#