Two German 5 Marks 1971 - East And West

Both coins are circulating at the same era, they are same size (29.0mm) but the West Germany 5 Marks is made of silver(62.5%) and weighs 11.04 grams. The East Germany 5 Marks is a Cu-Ni and weighs 9.54 grams.

Just seeing the above data, we know that the living standards of both East and West Germany differed significantly.

But can we use these data to deduce the exchange rate of the East Germany Mark with West Germany? That's the price of silver and Ni or Cu at 1970s? Or there is no relationship to the exchange rate as it was enacted by laws instead.

Just my fantastic imagination here!