Chapter EH, Problem 45R

Solution

Interpretation: The percentage of the fertilizer that is nitrogen needs to be calculated.

Concept Introduction: The percentage of A in B can be calculated as follows:

  $\%=\frac{\text{mass of A}}{\text{mass of B}}\times 100\%$

Here, the mass of A and B should have the same unit.

15%

The percentage of fertilizer that is nitrogen can be estimated by simply calculating the percentage of nitrogen in the fertilizer.

Here, the mass of the bag of fertilizer is 35 kg and the mass of nitrogen this fertilizer contains is 5.25 kg.

The percentage of the fertilizer which is nitrogen can be calculated as follows:

  $\%=\frac{m_{\text{N}}}{m_{\text{fertlizer}}^{}}\times 100\%$

Substitute the values,

  $\begin{array}{c}\%=\frac{5.25\text{ kg}}{35\text{ kg}}\times 100\%\\ =15\%\end{array}$

Thus, the percentage is 15%.