Given, Cov (x, y) =20
and variance of one of the variables is 16.
so the standard deviation SD is 4.
we know the formula,
r= cov (x, y) /(SD of x * SD of Y)
r= 20 /4 * SD of the other variable
r= 5/ SD of the other variable
we also know that coefficient of correlation, r, lies between -1 and +1 including them.
so, SD of the other variable has to be atleast 5 or more.
so the variance will be 5^2 = 25 atleast or more.
i dont know why the icai book says the answer is more than 100. if anybody can match the answer with book then please tell me.