In a certain chemical, the ratio of zinc to copper is 4 to 13 . A jar of the chemical contains 416 grams of copper. How many grams of zinc does it contain? grams of zinc

Step 1 ：The problem is asking for the amount of zinc in a jar of chemical, given the ratio of zinc to copper and the amount of copper.

Step 2 ：The ratio of zinc to copper is 4:13, which means for every 13 parts of copper, there are 4 parts of zinc.

Step 3 ：We can set up a proportion to solve for the amount of zinc. The proportion is \( \frac{4}{13} = \frac{x}{416} \), where x is the amount of zinc.

Step 4 ：We can solve for x by cross multiplying and dividing: \( x = \frac{4}{13} \times 416 \).

Step 5 ：Performing the calculation gives \( x = 128.0 \).

Step 6 ：Final Answer: The jar contains \( \boxed{128} \) grams of zinc.