How much silver in half dollar 1971?

Answer 1

None. The Mint changed the composition to copper-nickel that year. 1964 was the last year that the US Mint produced 90% silver coins, but subsequent coins do contain some silver. Since then, dimes, quarters, and halves are basically a big penny with a silver wash, although they retain the ridges around the rim of the coin. This was originally done to prevent counterfeiters from scraping silver (and gold) from the edges of US coinage. There will be no percentage in that enterprise again unless the price of copper rises high enough to make it worthwhile.