Each time a bar of soap is used, its volume decreases by #10%#. What is the minimum number of times a new bar would have to be used so that less than one-half its volume remains?

1 Answer
Oct 18, 2017

Answer:

7 times

Explanation:

The formula for this equation would be #V_i/2=V_i*0.9^x#

Dividing both sides by #V_i# gives #0.5=0.9^x#

Taking the log of both sides gives #log(0.5)=xlog(0.9)#

#x=log(0.5)/log(0.9)=6.58...~~7#

It can be used 7 times before less than half of its volume remains.