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The three parameters log$-$normal distribution Where a$,$ y $$and y$2$ are the parameters of this distribution. If mean of x $=14555$ cfs$,$ variance of x $=27300000$ cfs and skew$$ x$=1\mathrm{.}32$

a$)$ Using the estimation of the method of moments find a$,$ y $$and y$2$

b$)$ Find X$100$

c$)$ For discharge of $21000$ cfs what will be the return period?