i have 25 pounds of sliver alloy that cointain 8 ounces of p

i have 25 pounds of sliver alloy that cointain 8 ounces of pure silver per pound and 16 pounds that have 9.5 ounces of sliver per pound. How much copper must be added to the total so that I can make coins containing 7.5 ounces of silver per pound? Answer 5.933 pounds

Solution

25 pounds of silver aloy contains 8 ounces of pure silves per pound

25 pounds of silver aloy contains = 25*8 ounces of pure silves

= 200 ounces of pure silver

16 pounds of silver aloy contains 9.5 ounces of pure silves per pound

16 pounds of silver aloy contains = 16*9.5 ounces of pure silves

= 152 ounces of pure silver

7.5 ounces of silver per pound should be attained. Let t be the number of pounds of copper added to the mixture.

=> 25+16+t pounds has 7.5 ounces of silver per pound.

= (25+16+t)*7.5

But, we know total ounces of pure silver is 200+152 = 352 ounces

=> 352 = (25+16+t)*7.5

=> 352 = (41+t)*7.5

=> t = 5.933 pounds

Copper added = 5.933 pounds