A radioactive substance has an initial mass of 800 g. At the end of each day it retains 88 % of its mass from the previous day.
a. (i) Obtain an expression for the mass remaining after n days.
b. (ii) Compute the mass present after 15 days.
c. (iii) Find the least integer n for which the mass will be less than 100 g.
d. (iv) Calculate the total mass that decays during the first 15 days.