JEE Advanced 2015 Paper 2

For a radioactive material its activity A and rate of change of its activity R are defined as A=−d

N

d

tandR=−d

A

d

t,Where N(t) is the number of nuclei at time t.Two radioactive sources P(mean life τ) and Q(mean life 2τ) have the same activity at t= 0.their rates of changes of activities at t=2τ are RP‌and‌RQ,respectively.If

RP

RQ

=

n

e

,then the value of n is