For the problem below, I need an example of an ancillary statistic.

Problem 1 Let X1,.... X, be i.i.d random variables from the log-normal distribution with parameters DER, o' > 0, and p.d.f. f (C:0) = (rov2x) 'exp{ -(log(x) -0)?/(203)}, r>0 otherwise. Let o' > 0 be known.