The decay of a radioactive substance is modelled using the formula N=1000e−ktN = 1000e^{-kt}N=1000e−kt Where N N\,N is the number of atoms after t t\,t years and k k\,k is a positive constant.
Write down the number of atoms when the substance started to decay.
Given it takes 14.4 years for half of the substance to decay, find the value of k k\,k to three significant figures.
Calculate the number of atoms left when t=30t=30t=30.
