Consider a uniform distribution on the interval (a, ), where the values of a and are

Consider a uniform distribution on the interval (a, β), where the values of a and β are unknown, and suppose that the joint distribution of a and β is a bilateral bivariate Pareto distribution with y = 2. How large a random sample must be taken from the uniform distribution in order that the coefficient of variation (that is, the standard deviation divided by the mean) of the length β - a of the interval should be reduced to 0.01 or less?