Joe has a ring weighing 15 grams made of an alloy of 20 silver and the rest gold. He decides to melt down the rings and add enough silver to reduce the gold content to 67 . How many grams of silver should he add?
1) Moe earns 20 more than her husband Joe. Together they make 72000 per year. What is Joe’s annual salary
Joe has to add 2.9104 g of silver
To find out how many grams of silver Joe should add, we first need to determine the gold content in his ring.
Given that the ring weighs 15 grams and the gold content is the remaining percentage after subtracting the silver content (20%), we can calculate:
Gold content = 100% - Silver content
Gold content = 100% - 20% = 80%
Now, we need to find out the weight of gold in the ring.
Gold weight = Gold content * Total weight of the ring
Gold weight = 80% * 15 grams
Gold weight = 0.8 * 15 grams
Gold weight = 12 grams
Since Joe wants to reduce the gold content to 67%, we can calculate the new gold weight:
New gold weight = Gold content * Total weight of the ring
New gold weight = 67% * 15 grams
New gold weight = 0.67 * 15 grams
New gold weight = 10.05 grams
To determine the amount of silver to add, we need to find the difference between the initial gold weight and the new gold weight:
Silver to add = Difference in gold weight
Silver to add = New gold weight - Initial gold weight
Silver to add = 10.05 grams - 12 grams
Silver to add = -1.95 grams
Since the result is negative, it implies that Joe needs to add 1.95 grams of silver to adjust the gold content in the ring.