A 50 pound bag of 20-15-10 would contain how many pounds of phosphorus?

To determine how many pounds of phosphorus are in a 50-pound bag of fertilizer labeled 20-15-10, you need to understand what these numbers represent. They indicate the percentage by weight of three essential nutrients: nitrogen (the first number), phosphorus (the second number), and potassium (the third number).

In this case, the second number is 15, which means that 15% of the total weight of the fertilizer is phosphorus. To find the weight of phosphorus in a 50-pound bag, you can perform the following calculation:

1. Convert the percentage to a decimal: 15% becomes 0.15.
2. Multiply this decimal by the total weight of the fertilizer: ( 0.15 \times 50 , \text{pounds} = 7.5 , \text{pounds} ).

Therefore, a 50-pound bag of 20-15-10 fertilizer contains 7.5 pounds of phosphorus. This calculation confirms why the correct answer is indeed 7.5 pounds, representing the phosphorus content in the fertilizer formulation.